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diff --git a/README-uboot b/README-uboot new file mode 100644 index 00000000..8f816ad2 --- /dev/null +++ b/README-uboot @@ -0,0 +1,4977 @@ +# SPDX-License-Identifier: GPL-2.0+ +# +# (C) Copyright 2000 - 2013 +# Wolfgang Denk, DENX Software Engineering, wd@denx.de. + +Summary: +======== + +This directory contains the source code for U-Boot, a boot loader for +Embedded boards based on PowerPC, ARM, MIPS and several other +processors, which can be installed in a boot ROM and used to +initialize and test the hardware or to download and run application +code. + +The development of U-Boot is closely related to Linux: some parts of +the source code originate in the Linux source tree, we have some +header files in common, and special provision has been made to +support booting of Linux images. + +Some attention has been paid to make this software easily +configurable and extendable. For instance, all monitor commands are +implemented with the same call interface, so that it's very easy to +add new commands. Also, instead of permanently adding rarely used +code (for instance hardware test utilities) to the monitor, you can +load and run it dynamically. + + +Status: +======= + +In general, all boards for which a configuration option exists in the +Makefile have been tested to some extent and can be considered +"working". In fact, many of them are used in production systems. + +In case of problems see the CHANGELOG file to find out who contributed +the specific port. In addition, there are various MAINTAINERS files +scattered throughout the U-Boot source identifying the people or +companies responsible for various boards and subsystems. + +Note: As of August, 2010, there is no longer a CHANGELOG file in the +actual U-Boot source tree; however, it can be created dynamically +from the Git log using: + + make CHANGELOG + + +Where to get help: +================== + +In case you have questions about, problems with or contributions for +U-Boot, you should send a message to the U-Boot mailing list at +<u-boot@lists.denx.de>. There is also an archive of previous traffic +on the mailing list - please search the archive before asking FAQ's. +Please see http://lists.denx.de/pipermail/u-boot and +http://dir.gmane.org/gmane.comp.boot-loaders.u-boot + + +Where to get source code: +========================= + +The U-Boot source code is maintained in the Git repository at +git://www.denx.de/git/u-boot.git ; you can browse it online at +http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary + +The "snapshot" links on this page allow you to download tarballs of +any version you might be interested in. Official releases are also +available for FTP download from the ftp://ftp.denx.de/pub/u-boot/ +directory. + +Pre-built (and tested) images are available from +ftp://ftp.denx.de/pub/u-boot/images/ + + +Where we come from: +=================== + +- start from 8xxrom sources +- create PPCBoot project (http://sourceforge.net/projects/ppcboot) +- clean up code +- make it easier to add custom boards +- make it possible to add other [PowerPC] CPUs +- extend functions, especially: + * Provide extended interface to Linux boot loader + * S-Record download + * network boot + * PCMCIA / CompactFlash / ATA disk / SCSI ... boot +- create ARMBoot project (http://sourceforge.net/projects/armboot) +- add other CPU families (starting with ARM) +- create U-Boot project (http://sourceforge.net/projects/u-boot) +- current project page: see http://www.denx.de/wiki/U-Boot + + +Names and Spelling: +=================== + +The "official" name of this project is "Das U-Boot". The spelling +"U-Boot" shall be used in all written text (documentation, comments +in source files etc.). Example: + + This is the README file for the U-Boot project. + +File names etc. shall be based on the string "u-boot". Examples: + + include/asm-ppc/u-boot.h + + #include <asm/u-boot.h> + +Variable names, preprocessor constants etc. shall be either based on +the string "u_boot" or on "U_BOOT". Example: + + U_BOOT_VERSION u_boot_logo + IH_OS_U_BOOT u_boot_hush_start + + +Versioning: +=========== + +Starting with the release in October 2008, the names of the releases +were changed from numerical release numbers without deeper meaning +into a time stamp based numbering. Regular releases are identified by +names consisting of the calendar year and month of the release date. +Additional fields (if present) indicate release candidates or bug fix +releases in "stable" maintenance trees. + +Examples: + U-Boot v2009.11 - Release November 2009 + U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree + U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release + + +Directory Hierarchy: +==================== + +/arch Architecture specific files + /arc Files generic to ARC architecture + /arm Files generic to ARM architecture + /m68k Files generic to m68k architecture + /microblaze Files generic to microblaze architecture + /mips Files generic to MIPS architecture + /nds32 Files generic to NDS32 architecture + /nios2 Files generic to Altera NIOS2 architecture + /openrisc Files generic to OpenRISC architecture + /powerpc Files generic to PowerPC architecture + /riscv Files generic to RISC-V architecture + /sandbox Files generic to HW-independent "sandbox" + /sh Files generic to SH architecture + /x86 Files generic to x86 architecture +/api Machine/arch independent API for external apps +/board Board dependent files +/cmd U-Boot commands functions +/common Misc architecture independent functions +/configs Board default configuration files +/disk Code for disk drive partition handling +/doc Documentation (don't expect too much) +/drivers Commonly used device drivers +/dts Contains Makefile for building internal U-Boot fdt. +/examples Example code for standalone applications, etc. +/fs Filesystem code (cramfs, ext2, jffs2, etc.) +/include Header Files +/lib Library routines generic to all architectures +/Licenses Various license files +/net Networking code +/post Power On Self Test +/scripts Various build scripts and Makefiles +/test Various unit test files +/tools Tools to build S-Record or U-Boot images, etc. + +Software Configuration: +======================= + +Configuration is usually done using C preprocessor defines; the +rationale behind that is to avoid dead code whenever possible. + +There are two classes of configuration variables: + +* Configuration _OPTIONS_: + These are selectable by the user and have names beginning with + "CONFIG_". + +* Configuration _SETTINGS_: + These depend on the hardware etc. and should not be meddled with if + you don't know what you're doing; they have names beginning with + "CONFIG_SYS_". + +Previously, all configuration was done by hand, which involved creating +symbolic links and editing configuration files manually. More recently, +U-Boot has added the Kbuild infrastructure used by the Linux kernel, +allowing you to use the "make menuconfig" command to configure your +build. + + +Selection of Processor Architecture and Board Type: +--------------------------------------------------- + +For all supported boards there are ready-to-use default +configurations available; just type "make <board_name>_defconfig". + +Example: For a TQM823L module type: + + cd u-boot + make TQM823L_defconfig + +Note: If you're looking for the default configuration file for a board +you're sure used to be there but is now missing, check the file +doc/README.scrapyard for a list of no longer supported boards. + +Sandbox Environment: +-------------------- + +U-Boot can be built natively to run on a Linux host using the 'sandbox' +board. This allows feature development which is not board- or architecture- +specific to be undertaken on a native platform. The sandbox is also used to +run some of U-Boot's tests. + +See board/sandbox/README.sandbox for more details. + + +Board Initialisation Flow: +-------------------------- + +This is the intended start-up flow for boards. This should apply for both +SPL and U-Boot proper (i.e. they both follow the same rules). + +Note: "SPL" stands for "Secondary Program Loader," which is explained in +more detail later in this file. + +At present, SPL mostly uses a separate code path, but the function names +and roles of each function are the same. Some boards or architectures +may not conform to this. At least most ARM boards which use +CONFIG_SPL_FRAMEWORK conform to this. + +Execution typically starts with an architecture-specific (and possibly +CPU-specific) start.S file, such as: + + - arch/arm/cpu/armv7/start.S + - arch/powerpc/cpu/mpc83xx/start.S + - arch/mips/cpu/start.S + +and so on. From there, three functions are called; the purpose and +limitations of each of these functions are described below. + +lowlevel_init(): + - purpose: essential init to permit execution to reach board_init_f() + - no global_data or BSS + - there is no stack (ARMv7 may have one but it will soon be removed) + - must not set up SDRAM or use console + - must only do the bare minimum to allow execution to continue to + board_init_f() + - this is almost never needed + - return normally from this function + +board_init_f(): + - purpose: set up the machine ready for running board_init_r(): + i.e. SDRAM and serial UART + - global_data is available + - stack is in SRAM + - BSS is not available, so you cannot use global/static variables, + only stack variables and global_data + + Non-SPL-specific notes: + - dram_init() is called to set up DRAM. If already done in SPL this + can do nothing + + SPL-specific notes: + - you can override the entire board_init_f() function with your own + version as needed. + - preloader_console_init() can be called here in extremis + - should set up SDRAM, and anything needed to make the UART work + - these is no need to clear BSS, it will be done by crt0.S + - must return normally from this function (don't call board_init_r() + directly) + +Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at +this point the stack and global_data are relocated to below +CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of +memory. + +board_init_r(): + - purpose: main execution, common code + - global_data is available + - SDRAM is available + - BSS is available, all static/global variables can be used + - execution eventually continues to main_loop() + + Non-SPL-specific notes: + - U-Boot is relocated to the top of memory and is now running from + there. + + SPL-specific notes: + - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and + CONFIG_SPL_STACK_R_ADDR points into SDRAM + - preloader_console_init() can be called here - typically this is + done by selecting CONFIG_SPL_BOARD_INIT and then supplying a + spl_board_init() function containing this call + - loads U-Boot or (in falcon mode) Linux + + + +Configuration Options: +---------------------- + +Configuration depends on the combination of board and CPU type; all +such information is kept in a configuration file +"include/configs/<board_name>.h". + +Example: For a TQM823L module, all configuration settings are in +"include/configs/TQM823L.h". + + +Many of the options are named exactly as the corresponding Linux +kernel configuration options. The intention is to make it easier to +build a config tool - later. + +- ARM Platform Bus Type(CCI): + CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which + provides full cache coherency between two clusters of multi-core + CPUs and I/O coherency for devices and I/O masters + + CONFIG_SYS_FSL_HAS_CCI400 + + Defined For SoC that has cache coherent interconnect + CCN-400 + + CONFIG_SYS_FSL_HAS_CCN504 + + Defined for SoC that has cache coherent interconnect CCN-504 + +The following options need to be configured: + +- CPU Type: Define exactly one, e.g. CONFIG_MPC85XX. + +- Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS. + +- 85xx CPU Options: + CONFIG_SYS_PPC64 + + Specifies that the core is a 64-bit PowerPC implementation (implements + the "64" category of the Power ISA). This is necessary for ePAPR + compliance, among other possible reasons. + + CONFIG_SYS_FSL_TBCLK_DIV + + Defines the core time base clock divider ratio compared to the + system clock. On most PQ3 devices this is 8, on newer QorIQ + devices it can be 16 or 32. The ratio varies from SoC to Soc. + + CONFIG_SYS_FSL_PCIE_COMPAT + + Defines the string to utilize when trying to match PCIe device + tree nodes for the given platform. + + CONFIG_SYS_FSL_ERRATUM_A004510 + + Enables a workaround for erratum A004510. If set, + then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and + CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set. + + CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV + CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional) + + Defines one or two SoC revisions (low 8 bits of SVR) + for which the A004510 workaround should be applied. + + The rest of SVR is either not relevant to the decision + of whether the erratum is present (e.g. p2040 versus + p2041) or is implied by the build target, which controls + whether CONFIG_SYS_FSL_ERRATUM_A004510 is set. + + See Freescale App Note 4493 for more information about + this erratum. + + CONFIG_A003399_NOR_WORKAROUND + Enables a workaround for IFC erratum A003399. It is only + required during NOR boot. + + CONFIG_A008044_WORKAROUND + Enables a workaround for T1040/T1042 erratum A008044. It is only + required during NAND boot and valid for Rev 1.0 SoC revision + + CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY + + This is the value to write into CCSR offset 0x18600 + according to the A004510 workaround. + + CONFIG_SYS_FSL_DSP_DDR_ADDR + This value denotes start offset of DDR memory which is + connected exclusively to the DSP cores. + + CONFIG_SYS_FSL_DSP_M2_RAM_ADDR + This value denotes start offset of M2 memory + which is directly connected to the DSP core. + + CONFIG_SYS_FSL_DSP_M3_RAM_ADDR + This value denotes start offset of M3 memory which is directly + connected to the DSP core. + + CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT + This value denotes start offset of DSP CCSR space. + + CONFIG_SYS_FSL_SINGLE_SOURCE_CLK + Single Source Clock is clocking mode present in some of FSL SoC's. + In this mode, a single differential clock is used to supply + clocks to the sysclock, ddrclock and usbclock. + + CONFIG_SYS_CPC_REINIT_F + This CONFIG is defined when the CPC is configured as SRAM at the + time of U-Boot entry and is required to be re-initialized. + + CONFIG_DEEP_SLEEP + Indicates this SoC supports deep sleep feature. If deep sleep is + supported, core will start to execute uboot when wakes up. + +- Generic CPU options: + CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN + + Defines the endianess of the CPU. Implementation of those + values is arch specific. + + CONFIG_SYS_FSL_DDR + Freescale DDR driver in use. This type of DDR controller is + found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core + SoCs. + + CONFIG_SYS_FSL_DDR_ADDR + Freescale DDR memory-mapped register base. + + CONFIG_SYS_FSL_DDR_EMU + Specify emulator support for DDR. Some DDR features such as + deskew training are not available. + + CONFIG_SYS_FSL_DDRC_GEN1 + Freescale DDR1 controller. + + CONFIG_SYS_FSL_DDRC_GEN2 + Freescale DDR2 controller. + + CONFIG_SYS_FSL_DDRC_GEN3 + Freescale DDR3 controller. + + CONFIG_SYS_FSL_DDRC_GEN4 + Freescale DDR4 controller. + + CONFIG_SYS_FSL_DDRC_ARM_GEN3 + Freescale DDR3 controller for ARM-based SoCs. + + CONFIG_SYS_FSL_DDR1 + Board config to use DDR1. It can be enabled for SoCs with + Freescale DDR1 or DDR2 controllers, depending on the board + implemetation. + + CONFIG_SYS_FSL_DDR2 + Board config to use DDR2. It can be enabled for SoCs with + Freescale DDR2 or DDR3 controllers, depending on the board + implementation. + + CONFIG_SYS_FSL_DDR3 + Board config to use DDR3. It can be enabled for SoCs with + Freescale DDR3 or DDR3L controllers. + + CONFIG_SYS_FSL_DDR3L + Board config to use DDR3L. It can be enabled for SoCs with + DDR3L controllers. + + CONFIG_SYS_FSL_DDR4 + Board config to use DDR4. It can be enabled for SoCs with + DDR4 controllers. + + CONFIG_SYS_FSL_IFC_BE + Defines the IFC controller register space as Big Endian + + CONFIG_SYS_FSL_IFC_LE + Defines the IFC controller register space as Little Endian + + CONFIG_SYS_FSL_IFC_CLK_DIV + Defines divider of platform clock(clock input to IFC controller). + + CONFIG_SYS_FSL_LBC_CLK_DIV + Defines divider of platform clock(clock input to eLBC controller). + + CONFIG_SYS_FSL_PBL_PBI + It enables addition of RCW (Power on reset configuration) in built image. + Please refer doc/README.pblimage for more details + + CONFIG_SYS_FSL_PBL_RCW + It adds PBI(pre-boot instructions) commands in u-boot build image. + PBI commands can be used to configure SoC before it starts the execution. + Please refer doc/README.pblimage for more details + + CONFIG_SYS_FSL_DDR_BE + Defines the DDR controller register space as Big Endian + + CONFIG_SYS_FSL_DDR_LE + Defines the DDR controller register space as Little Endian + + CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY + Physical address from the view of DDR controllers. It is the + same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But + it could be different for ARM SoCs. + + CONFIG_SYS_FSL_DDR_INTLV_256B + DDR controller interleaving on 256-byte. This is a special + interleaving mode, handled by Dickens for Freescale layerscape + SoCs with ARM core. + + CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS + Number of controllers used as main memory. + + CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS + Number of controllers used for other than main memory. + + CONFIG_SYS_FSL_HAS_DP_DDR + Defines the SoC has DP-DDR used for DPAA. + + CONFIG_SYS_FSL_SEC_BE + Defines the SEC controller register space as Big Endian + + CONFIG_SYS_FSL_SEC_LE + Defines the SEC controller register space as Little Endian + +- MIPS CPU options: + CONFIG_SYS_INIT_SP_OFFSET + + Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack + pointer. This is needed for the temporary stack before + relocation. + + CONFIG_XWAY_SWAP_BYTES + + Enable compilation of tools/xway-swap-bytes needed for Lantiq + XWAY SoCs for booting from NOR flash. The U-Boot image needs to + be swapped if a flash programmer is used. + +- ARM options: + CONFIG_SYS_EXCEPTION_VECTORS_HIGH + + Select high exception vectors of the ARM core, e.g., do not + clear the V bit of the c1 register of CP15. + + COUNTER_FREQUENCY + Generic timer clock source frequency. + + COUNTER_FREQUENCY_REAL + Generic timer clock source frequency if the real clock is + different from COUNTER_FREQUENCY, and can only be determined + at run time. + +- Tegra SoC options: + CONFIG_TEGRA_SUPPORT_NON_SECURE + + Support executing U-Boot in non-secure (NS) mode. Certain + impossible actions will be skipped if the CPU is in NS mode, + such as ARM architectural timer initialization. + +- Linux Kernel Interface: + CONFIG_CLOCKS_IN_MHZ + + U-Boot stores all clock information in Hz + internally. For binary compatibility with older Linux + kernels (which expect the clocks passed in the + bd_info data to be in MHz) the environment variable + "clocks_in_mhz" can be defined so that U-Boot + converts clock data to MHZ before passing it to the + Linux kernel. + When CONFIG_CLOCKS_IN_MHZ is defined, a definition of + "clocks_in_mhz=1" is automatically included in the + default environment. + + CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only] + + When transferring memsize parameter to Linux, some versions + expect it to be in bytes, others in MB. + Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes. + + CONFIG_OF_LIBFDT + + New kernel versions are expecting firmware settings to be + passed using flattened device trees (based on open firmware + concepts). + + CONFIG_OF_LIBFDT + * New libfdt-based support + * Adds the "fdt" command + * The bootm command automatically updates the fdt + + OF_TBCLK - The timebase frequency. + OF_STDOUT_PATH - The path to the console device + + boards with QUICC Engines require OF_QE to set UCC MAC + addresses + + CONFIG_OF_BOARD_SETUP + + Board code has addition modification that it wants to make + to the flat device tree before handing it off to the kernel + + CONFIG_OF_SYSTEM_SETUP + + Other code has addition modification that it wants to make + to the flat device tree before handing it off to the kernel. + This causes ft_system_setup() to be called before booting + the kernel. + + CONFIG_OF_IDE_FIXUP + + U-Boot can detect if an IDE device is present or not. + If not, and this new config option is activated, U-Boot + removes the ATA node from the DTS before booting Linux, + so the Linux IDE driver does not probe the device and + crash. This is needed for buggy hardware (uc101) where + no pull down resistor is connected to the signal IDE5V_DD7. + + CONFIG_MACH_TYPE [relevant for ARM only][mandatory] + + This setting is mandatory for all boards that have only one + machine type and must be used to specify the machine type + number as it appears in the ARM machine registry + (see http://www.arm.linux.org.uk/developer/machines/). + Only boards that have multiple machine types supported + in a single configuration file and the machine type is + runtime discoverable, do not have to use this setting. + +- vxWorks boot parameters: + + bootvx constructs a valid bootline using the following + environments variables: bootdev, bootfile, ipaddr, netmask, + serverip, gatewayip, hostname, othbootargs. + It loads the vxWorks image pointed bootfile. + + Note: If a "bootargs" environment is defined, it will overwride + the defaults discussed just above. + +- Cache Configuration: + CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot + +- Cache Configuration for ARM: + CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache + controller + CONFIG_SYS_PL310_BASE - Physical base address of PL310 + controller register space + +- Serial Ports: + CONFIG_PL010_SERIAL + + Define this if you want support for Amba PrimeCell PL010 UARTs. + + CONFIG_PL011_SERIAL + + Define this if you want support for Amba PrimeCell PL011 UARTs. + + CONFIG_PL011_CLOCK + + If you have Amba PrimeCell PL011 UARTs, set this variable to + the clock speed of the UARTs. + + CONFIG_PL01x_PORTS + + If you have Amba PrimeCell PL010 or PL011 UARTs on your board, + define this to a list of base addresses for each (supported) + port. See e.g. include/configs/versatile.h + + CONFIG_SERIAL_HW_FLOW_CONTROL + + Define this variable to enable hw flow control in serial driver. + Current user of this option is drivers/serial/nsl16550.c driver + +- Console Baudrate: + CONFIG_BAUDRATE - in bps + Select one of the baudrates listed in + CONFIG_SYS_BAUDRATE_TABLE, see below. + +- Autoboot Command: + CONFIG_BOOTCOMMAND + Only needed when CONFIG_BOOTDELAY is enabled; + define a command string that is automatically executed + when no character is read on the console interface + within "Boot Delay" after reset. + + CONFIG_RAMBOOT and CONFIG_NFSBOOT + The value of these goes into the environment as + "ramboot" and "nfsboot" respectively, and can be used + as a convenience, when switching between booting from + RAM and NFS. + +- Serial Download Echo Mode: + CONFIG_LOADS_ECHO + If defined to 1, all characters received during a + serial download (using the "loads" command) are + echoed back. This might be needed by some terminal + emulations (like "cu"), but may as well just take + time on others. This setting #define's the initial + value of the "loads_echo" environment variable. + +- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined) + CONFIG_KGDB_BAUDRATE + Select one of the baudrates listed in + CONFIG_SYS_BAUDRATE_TABLE, see below. + +- Removal of commands + If no commands are needed to boot, you can disable + CONFIG_CMDLINE to remove them. In this case, the command line + will not be available, and when U-Boot wants to execute the + boot command (on start-up) it will call board_run_command() + instead. This can reduce image size significantly for very + simple boot procedures. + +- Regular expression support: + CONFIG_REGEX + If this variable is defined, U-Boot is linked against + the SLRE (Super Light Regular Expression) library, + which adds regex support to some commands, as for + example "env grep" and "setexpr". + +- Device tree: + CONFIG_OF_CONTROL + If this variable is defined, U-Boot will use a device tree + to configure its devices, instead of relying on statically + compiled #defines in the board file. This option is + experimental and only available on a few boards. The device + tree is available in the global data as gd->fdt_blob. + + U-Boot needs to get its device tree from somewhere. This can + be done using one of the three options below: + + CONFIG_OF_EMBED + If this variable is defined, U-Boot will embed a device tree + binary in its image. This device tree file should be in the + board directory and called <soc>-<board>.dts. The binary file + is then picked up in board_init_f() and made available through + the global data structure as gd->fdt_blob. + + CONFIG_OF_SEPARATE + If this variable is defined, U-Boot will build a device tree + binary. It will be called u-boot.dtb. Architecture-specific + code will locate it at run-time. Generally this works by: + + cat u-boot.bin u-boot.dtb >image.bin + + and in fact, U-Boot does this for you, creating a file called + u-boot-dtb.bin which is useful in the common case. You can + still use the individual files if you need something more + exotic. + + CONFIG_OF_BOARD + If this variable is defined, U-Boot will use the device tree + provided by the board at runtime instead of embedding one with + the image. Only boards defining board_fdt_blob_setup() support + this option (see include/fdtdec.h file). + +- Watchdog: + CONFIG_WATCHDOG + If this variable is defined, it enables watchdog + support for the SoC. There must be support in the SoC + specific code for a watchdog. For the 8xx + CPUs, the SIU Watchdog feature is enabled in the SYPCR + register. When supported for a specific SoC is + available, then no further board specific code should + be needed to use it. + + CONFIG_HW_WATCHDOG + When using a watchdog circuitry external to the used + SoC, then define this variable and provide board + specific code for the "hw_watchdog_reset" function. + +- Real-Time Clock: + + When CONFIG_CMD_DATE is selected, the type of the RTC + has to be selected, too. Define exactly one of the + following options: + + CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC + CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC + CONFIG_RTC_MC146818 - use MC146818 RTC + CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC + CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC + CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC + CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC + CONFIG_RTC_DS164x - use Dallas DS164x RTC + CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC + CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC + CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337 + CONFIG_SYS_RV3029_TCR - enable trickle charger on + RV3029 RTC. + + Note that if the RTC uses I2C, then the I2C interface + must also be configured. See I2C Support, below. + +- GPIO Support: + CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO + + The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of + chip-ngpio pairs that tell the PCA953X driver the number of + pins supported by a particular chip. + + Note that if the GPIO device uses I2C, then the I2C interface + must also be configured. See I2C Support, below. + +- I/O tracing: + When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O + accesses and can checksum them or write a list of them out + to memory. See the 'iotrace' command for details. This is + useful for testing device drivers since it can confirm that + the driver behaves the same way before and after a code + change. Currently this is supported on sandbox and arm. To + add support for your architecture, add '#include <iotrace.h>' + to the bottom of arch/<arch>/include/asm/io.h and test. + + Example output from the 'iotrace stats' command is below. + Note that if the trace buffer is exhausted, the checksum will + still continue to operate. + + iotrace is enabled + Start: 10000000 (buffer start address) + Size: 00010000 (buffer size) + Offset: 00000120 (current buffer offset) + Output: 10000120 (start + offset) + Count: 00000018 (number of trace records) + CRC32: 9526fb66 (CRC32 of all trace records) + +- Timestamp Support: + + When CONFIG_TIMESTAMP is selected, the timestamp + (date and time) of an image is printed by image + commands like bootm or iminfo. This option is + automatically enabled when you select CONFIG_CMD_DATE . + +- Partition Labels (disklabels) Supported: + Zero or more of the following: + CONFIG_MAC_PARTITION Apple's MacOS partition table. + CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc. + CONFIG_EFI_PARTITION GPT partition table, common when EFI is the + bootloader. Note 2TB partition limit; see + disk/part_efi.c + CONFIG_SCSI) you must configure support for at + least one non-MTD partition type as well. + +- IDE Reset method: + CONFIG_IDE_RESET_ROUTINE - this is defined in several + board configurations files but used nowhere! + + CONFIG_IDE_RESET - is this is defined, IDE Reset will + be performed by calling the function + ide_set_reset(int reset) + which has to be defined in a board specific file + +- ATAPI Support: + CONFIG_ATAPI + + Set this to enable ATAPI support. + +- LBA48 Support + CONFIG_LBA48 + + Set this to enable support for disks larger than 137GB + Also look at CONFIG_SYS_64BIT_LBA. + Whithout these , LBA48 support uses 32bit variables and will 'only' + support disks up to 2.1TB. + + CONFIG_SYS_64BIT_LBA: + When enabled, makes the IDE subsystem use 64bit sector addresses. + Default is 32bit. + +- SCSI Support: + CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and + CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID * + CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the + maximum numbers of LUNs, SCSI ID's and target + devices. + + The environment variable 'scsidevs' is set to the number of + SCSI devices found during the last scan. + +- NETWORK Support (PCI): + CONFIG_E1000 + Support for Intel 8254x/8257x gigabit chips. + + CONFIG_E1000_SPI + Utility code for direct access to the SPI bus on Intel 8257x. + This does not do anything useful unless you set at least one + of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC. + + CONFIG_E1000_SPI_GENERIC + Allow generic access to the SPI bus on the Intel 8257x, for + example with the "sspi" command. + + CONFIG_EEPRO100 + Support for Intel 82557/82559/82559ER chips. + Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM + write routine for first time initialisation. + + CONFIG_TULIP + Support for Digital 2114x chips. + Optional CONFIG_TULIP_SELECT_MEDIA for board specific + modem chip initialisation (KS8761/QS6611). + + CONFIG_NATSEMI + Support for National dp83815 chips. + + CONFIG_NS8382X + Support for National dp8382[01] gigabit chips. + +- NETWORK Support (other): + + CONFIG_DRIVER_AT91EMAC + Support for AT91RM9200 EMAC. + + CONFIG_RMII + Define this to use reduced MII inteface + + CONFIG_DRIVER_AT91EMAC_QUIET + If this defined, the driver is quiet. + The driver doen't show link status messages. + + CONFIG_CALXEDA_XGMAC + Support for the Calxeda XGMAC device + + CONFIG_LAN91C96 + Support for SMSC's LAN91C96 chips. + + CONFIG_LAN91C96_USE_32_BIT + Define this to enable 32 bit addressing + + CONFIG_SMC91111 + Support for SMSC's LAN91C111 chip + + CONFIG_SMC91111_BASE + Define this to hold the physical address + of the device (I/O space) + + CONFIG_SMC_USE_32_BIT + Define this if data bus is 32 bits + + CONFIG_SMC_USE_IOFUNCS + Define this to use i/o functions instead of macros + (some hardware wont work with macros) + + CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT + Define this if you have more then 3 PHYs. + + CONFIG_FTGMAC100 + Support for Faraday's FTGMAC100 Gigabit SoC Ethernet + + CONFIG_FTGMAC100_EGIGA + Define this to use GE link update with gigabit PHY. + Define this if FTGMAC100 is connected to gigabit PHY. + If your system has 10/100 PHY only, it might not occur + wrong behavior. Because PHY usually return timeout or + useless data when polling gigabit status and gigabit + control registers. This behavior won't affect the + correctnessof 10/100 link speed update. + + CONFIG_SH_ETHER + Support for Renesas on-chip Ethernet controller + + CONFIG_SH_ETHER_USE_PORT + Define the number of ports to be used + + CONFIG_SH_ETHER_PHY_ADDR + Define the ETH PHY's address + + CONFIG_SH_ETHER_CACHE_WRITEBACK + If this option is set, the driver enables cache flush. + +- PWM Support: + CONFIG_PWM_IMX + Support for PWM module on the imx6. + +- TPM Support: + CONFIG_TPM + Support TPM devices. + + CONFIG_TPM_TIS_INFINEON + Support for Infineon i2c bus TPM devices. Only one device + per system is supported at this time. + + CONFIG_TPM_TIS_I2C_BURST_LIMITATION + Define the burst count bytes upper limit + + CONFIG_TPM_ST33ZP24 + Support for STMicroelectronics TPM devices. Requires DM_TPM support. + + CONFIG_TPM_ST33ZP24_I2C + Support for STMicroelectronics ST33ZP24 I2C devices. + Requires TPM_ST33ZP24 and I2C. + + CONFIG_TPM_ST33ZP24_SPI + Support for STMicroelectronics ST33ZP24 SPI devices. + Requires TPM_ST33ZP24 and SPI. + + CONFIG_TPM_ATMEL_TWI + Support for Atmel TWI TPM device. Requires I2C support. + + CONFIG_TPM_TIS_LPC + Support for generic parallel port TPM devices. Only one device + per system is supported at this time. + + CONFIG_TPM_TIS_BASE_ADDRESS + Base address where the generic TPM device is mapped + to. Contemporary x86 systems usually map it at + 0xfed40000. + + CONFIG_TPM + Define this to enable the TPM support library which provides + functional interfaces to some TPM commands. + Requires support for a TPM device. + + CONFIG_TPM_AUTH_SESSIONS + Define this to enable authorized functions in the TPM library. + Requires CONFIG_TPM and CONFIG_SHA1. + +- USB Support: + At the moment only the UHCI host controller is + supported (PIP405, MIP405); define + CONFIG_USB_UHCI to enable it. + define CONFIG_USB_KEYBOARD to enable the USB Keyboard + and define CONFIG_USB_STORAGE to enable the USB + storage devices. + Note: + Supported are USB Keyboards and USB Floppy drives + (TEAC FD-05PUB). + + CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the + txfilltuning field in the EHCI controller on reset. + + CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2 + HW module registers. + +- USB Device: + Define the below if you wish to use the USB console. + Once firmware is rebuilt from a serial console issue the + command "setenv stdin usbtty; setenv stdout usbtty" and + attach your USB cable. The Unix command "dmesg" should print + it has found a new device. The environment variable usbtty + can be set to gserial or cdc_acm to enable your device to + appear to a USB host as a Linux gserial device or a + Common Device Class Abstract Control Model serial device. + If you select usbtty = gserial you should be able to enumerate + a Linux host by + # modprobe usbserial vendor=0xVendorID product=0xProductID + else if using cdc_acm, simply setting the environment + variable usbtty to be cdc_acm should suffice. The following + might be defined in YourBoardName.h + + CONFIG_USB_DEVICE + Define this to build a UDC device + + CONFIG_USB_TTY + Define this to have a tty type of device available to + talk to the UDC device + + CONFIG_USBD_HS + Define this to enable the high speed support for usb + device and usbtty. If this feature is enabled, a routine + int is_usbd_high_speed(void) + also needs to be defined by the driver to dynamically poll + whether the enumeration has succeded at high speed or full + speed. + + CONFIG_SYS_CONSOLE_IS_IN_ENV + Define this if you want stdin, stdout &/or stderr to + be set to usbtty. + + If you have a USB-IF assigned VendorID then you may wish to + define your own vendor specific values either in BoardName.h + or directly in usbd_vendor_info.h. If you don't define + CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME, + CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot + should pretend to be a Linux device to it's target host. + + CONFIG_USBD_MANUFACTURER + Define this string as the name of your company for + - CONFIG_USBD_MANUFACTURER "my company" + + CONFIG_USBD_PRODUCT_NAME + Define this string as the name of your product + - CONFIG_USBD_PRODUCT_NAME "acme usb device" + + CONFIG_USBD_VENDORID + Define this as your assigned Vendor ID from the USB + Implementors Forum. This *must* be a genuine Vendor ID + to avoid polluting the USB namespace. + - CONFIG_USBD_VENDORID 0xFFFF + + CONFIG_USBD_PRODUCTID + Define this as the unique Product ID + for your device + - CONFIG_USBD_PRODUCTID 0xFFFF + +- ULPI Layer Support: + The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via + the generic ULPI layer. The generic layer accesses the ULPI PHY + via the platform viewport, so you need both the genric layer and + the viewport enabled. Currently only Chipidea/ARC based + viewport is supported. + To enable the ULPI layer support, define CONFIG_USB_ULPI and + CONFIG_USB_ULPI_VIEWPORT in your board configuration file. + If your ULPI phy needs a different reference clock than the + standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to + the appropriate value in Hz. + +- MMC Support: + The MMC controller on the Intel PXA is supported. To + enable this define CONFIG_MMC. The MMC can be + accessed from the boot prompt by mapping the device + to physical memory similar to flash. Command line is + enabled with CONFIG_CMD_MMC. The MMC driver also works with + the FAT fs. This is enabled with CONFIG_CMD_FAT. + + CONFIG_SH_MMCIF + Support for Renesas on-chip MMCIF controller + + CONFIG_SH_MMCIF_ADDR + Define the base address of MMCIF registers + + CONFIG_SH_MMCIF_CLK + Define the clock frequency for MMCIF + +- USB Device Firmware Update (DFU) class support: + CONFIG_DFU_OVER_USB + This enables the USB portion of the DFU USB class + + CONFIG_DFU_NAND + This enables support for exposing NAND devices via DFU. + + CONFIG_DFU_RAM + This enables support for exposing RAM via DFU. + Note: DFU spec refer to non-volatile memory usage, but + allow usages beyond the scope of spec - here RAM usage, + one that would help mostly the developer. + + CONFIG_SYS_DFU_DATA_BUF_SIZE + Dfu transfer uses a buffer before writing data to the + raw storage device. Make the size (in bytes) of this buffer + configurable. The size of this buffer is also configurable + through the "dfu_bufsiz" environment variable. + + CONFIG_SYS_DFU_MAX_FILE_SIZE + When updating files rather than the raw storage device, + we use a static buffer to copy the file into and then write + the buffer once we've been given the whole file. Define + this to the maximum filesize (in bytes) for the buffer. + Default is 4 MiB if undefined. + + DFU_DEFAULT_POLL_TIMEOUT + Poll timeout [ms], is the timeout a device can send to the + host. The host must wait for this timeout before sending + a subsequent DFU_GET_STATUS request to the device. + + DFU_MANIFEST_POLL_TIMEOUT + Poll timeout [ms], which the device sends to the host when + entering dfuMANIFEST state. Host waits this timeout, before + sending again an USB request to the device. + +- Journaling Flash filesystem support: + CONFIG_JFFS2_NAND + Define these for a default partition on a NAND device + + CONFIG_SYS_JFFS2_FIRST_SECTOR, + CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS + Define these for a default partition on a NOR device + +- Keyboard Support: + See Kconfig help for available keyboard drivers. + + CONFIG_KEYBOARD + + Define this to enable a custom keyboard support. + This simply calls drv_keyboard_init() which must be + defined in your board-specific files. This option is deprecated + and is only used by novena. For new boards, use driver model + instead. + +- Video support: + CONFIG_FSL_DIU_FB + Enable the Freescale DIU video driver. Reference boards for + SOCs that have a DIU should define this macro to enable DIU + support, and should also define these other macros: + + CONFIG_SYS_DIU_ADDR + CONFIG_VIDEO + CONFIG_CFB_CONSOLE + CONFIG_VIDEO_SW_CURSOR + CONFIG_VGA_AS_SINGLE_DEVICE + CONFIG_VIDEO_LOGO + CONFIG_VIDEO_BMP_LOGO + + The DIU driver will look for the 'video-mode' environment + variable, and if defined, enable the DIU as a console during + boot. See the documentation file doc/README.video for a + description of this variable. + +- LCD Support: CONFIG_LCD + + Define this to enable LCD support (for output to LCD + display); also select one of the supported displays + by defining one of these: + + CONFIG_ATMEL_LCD: + + HITACHI TX09D70VM1CCA, 3.5", 240x320. + + CONFIG_NEC_NL6448AC33: + + NEC NL6448AC33-18. Active, color, single scan. + + CONFIG_NEC_NL6448BC20 + + NEC NL6448BC20-08. 6.5", 640x480. + Active, color, single scan. + + CONFIG_NEC_NL6448BC33_54 + + NEC NL6448BC33-54. 10.4", 640x480. + Active, color, single scan. + + CONFIG_SHARP_16x9 + + Sharp 320x240. Active, color, single scan. + It isn't 16x9, and I am not sure what it is. + + CONFIG_SHARP_LQ64D341 + + Sharp LQ64D341 display, 640x480. + Active, color, single scan. + + CONFIG_HLD1045 + + HLD1045 display, 640x480. + Active, color, single scan. + + CONFIG_OPTREX_BW + + Optrex CBL50840-2 NF-FW 99 22 M5 + or + Hitachi LMG6912RPFC-00T + or + Hitachi SP14Q002 + + 320x240. Black & white. + + CONFIG_LCD_ALIGNMENT + + Normally the LCD is page-aligned (typically 4KB). If this is + defined then the LCD will be aligned to this value instead. + For ARM it is sometimes useful to use MMU_SECTION_SIZE + here, since it is cheaper to change data cache settings on + a per-section basis. + + + CONFIG_LCD_ROTATION + + Sometimes, for example if the display is mounted in portrait + mode or even if it's mounted landscape but rotated by 180degree, + we need to rotate our content of the display relative to the + framebuffer, so that user can read the messages which are + printed out. + Once CONFIG_LCD_ROTATION is defined, the lcd_console will be + initialized with a given rotation from "vl_rot" out of + "vidinfo_t" which is provided by the board specific code. + The value for vl_rot is coded as following (matching to + fbcon=rotate:<n> linux-kernel commandline): + 0 = no rotation respectively 0 degree + 1 = 90 degree rotation + 2 = 180 degree rotation + 3 = 270 degree rotation + + If CONFIG_LCD_ROTATION is not defined, the console will be + initialized with 0degree rotation. + + CONFIG_LCD_BMP_RLE8 + + Support drawing of RLE8-compressed bitmaps on the LCD. + + CONFIG_I2C_EDID + + Enables an 'i2c edid' command which can read EDID + information over I2C from an attached LCD display. + +- Splash Screen Support: CONFIG_SPLASH_SCREEN + + If this option is set, the environment is checked for + a variable "splashimage". If found, the usual display + of logo, copyright and system information on the LCD + is suppressed and the BMP image at the address + specified in "splashimage" is loaded instead. The + console is redirected to the "nulldev", too. This + allows for a "silent" boot where a splash screen is + loaded very quickly after power-on. + + CONFIG_SPLASHIMAGE_GUARD + + If this option is set, then U-Boot will prevent the environment + variable "splashimage" from being set to a problematic address + (see doc/README.displaying-bmps). + This option is useful for targets where, due to alignment + restrictions, an improperly aligned BMP image will cause a data + abort. If you think you will not have problems with unaligned + accesses (for example because your toolchain prevents them) + there is no need to set this option. + + CONFIG_SPLASH_SCREEN_ALIGN + + If this option is set the splash image can be freely positioned + on the screen. Environment variable "splashpos" specifies the + position as "x,y". If a positive number is given it is used as + number of pixel from left/top. If a negative number is given it + is used as number of pixel from right/bottom. You can also + specify 'm' for centering the image. + + Example: + setenv splashpos m,m + => image at center of screen + + setenv splashpos 30,20 + => image at x = 30 and y = 20 + + setenv splashpos -10,m + => vertically centered image + at x = dspWidth - bmpWidth - 9 + +- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP + + If this option is set, additionally to standard BMP + images, gzipped BMP images can be displayed via the + splashscreen support or the bmp command. + +- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8 + + If this option is set, 8-bit RLE compressed BMP images + can be displayed via the splashscreen support or the + bmp command. + +- Compression support: + CONFIG_GZIP + + Enabled by default to support gzip compressed images. + + CONFIG_BZIP2 + + If this option is set, support for bzip2 compressed + images is included. If not, only uncompressed and gzip + compressed images are supported. + + NOTE: the bzip2 algorithm requires a lot of RAM, so + the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should + be at least 4MB. + +- MII/PHY support: + CONFIG_PHY_CLOCK_FREQ (ppc4xx) + + The clock frequency of the MII bus + + CONFIG_PHY_RESET_DELAY + + Some PHY like Intel LXT971A need extra delay after + reset before any MII register access is possible. + For such PHY, set this option to the usec delay + required. (minimum 300usec for LXT971A) + + CONFIG_PHY_CMD_DELAY (ppc4xx) + + Some PHY like Intel LXT971A need extra delay after + command issued before MII status register can be read + +- IP address: + CONFIG_IPADDR + + Define a default value for the IP address to use for + the default Ethernet interface, in case this is not + determined through e.g. bootp. + (Environment variable "ipaddr") + +- Server IP address: + CONFIG_SERVERIP + + Defines a default value for the IP address of a TFTP + server to contact when using the "tftboot" command. + (Environment variable "serverip") + + CONFIG_KEEP_SERVERADDR + + Keeps the server's MAC address, in the env 'serveraddr' + for passing to bootargs (like Linux's netconsole option) + +- Gateway IP address: + CONFIG_GATEWAYIP + + Defines a default value for the IP address of the + default router where packets to other networks are + sent to. + (Environment variable "gatewayip") + +- Subnet mask: + CONFIG_NETMASK + + Defines a default value for the subnet mask (or + routing prefix) which is used to determine if an IP + address belongs to the local subnet or needs to be + forwarded through a router. + (Environment variable "netmask") + +- BOOTP Recovery Mode: + CONFIG_BOOTP_RANDOM_DELAY + + If you have many targets in a network that try to + boot using BOOTP, you may want to avoid that all + systems send out BOOTP requests at precisely the same + moment (which would happen for instance at recovery + from a power failure, when all systems will try to + boot, thus flooding the BOOTP server. Defining + CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be + inserted before sending out BOOTP requests. The + following delays are inserted then: + + 1st BOOTP request: delay 0 ... 1 sec + 2nd BOOTP request: delay 0 ... 2 sec + 3rd BOOTP request: delay 0 ... 4 sec + 4th and following + BOOTP requests: delay 0 ... 8 sec + + CONFIG_BOOTP_ID_CACHE_SIZE + + BOOTP packets are uniquely identified using a 32-bit ID. The + server will copy the ID from client requests to responses and + U-Boot will use this to determine if it is the destination of + an incoming response. Some servers will check that addresses + aren't in use before handing them out (usually using an ARP + ping) and therefore take up to a few hundred milliseconds to + respond. Network congestion may also influence the time it + takes for a response to make it back to the client. If that + time is too long, U-Boot will retransmit requests. In order + to allow earlier responses to still be accepted after these + retransmissions, U-Boot's BOOTP client keeps a small cache of + IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this + cache. The default is to keep IDs for up to four outstanding + requests. Increasing this will allow U-Boot to accept offers + from a BOOTP client in networks with unusually high latency. + +- DHCP Advanced Options: + You can fine tune the DHCP functionality by defining + CONFIG_BOOTP_* symbols: + + CONFIG_BOOTP_NISDOMAIN + CONFIG_BOOTP_BOOTFILESIZE + CONFIG_BOOTP_SEND_HOSTNAME + CONFIG_BOOTP_NTPSERVER + CONFIG_BOOTP_TIMEOFFSET + CONFIG_BOOTP_VENDOREX + CONFIG_BOOTP_MAY_FAIL + + CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip + environment variable, not the BOOTP server. + + CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found + after the configured retry count, the call will fail + instead of starting over. This can be used to fail over + to Link-local IP address configuration if the DHCP server + is not available. + + CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable + to do a dynamic update of a DNS server. To do this, they + need the hostname of the DHCP requester. + If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content + of the "hostname" environment variable is passed as + option 12 to the DHCP server. + + CONFIG_BOOTP_DHCP_REQUEST_DELAY + + A 32bit value in microseconds for a delay between + receiving a "DHCP Offer" and sending the "DHCP Request". + This fixes a problem with certain DHCP servers that don't + respond 100% of the time to a "DHCP request". E.g. On an + AT91RM9200 processor running at 180MHz, this delay needed + to be *at least* 15,000 usec before a Windows Server 2003 + DHCP server would reply 100% of the time. I recommend at + least 50,000 usec to be safe. The alternative is to hope + that one of the retries will be successful but note that + the DHCP timeout and retry process takes a longer than + this delay. + + - Link-local IP address negotiation: + Negotiate with other link-local clients on the local network + for an address that doesn't require explicit configuration. + This is especially useful if a DHCP server cannot be guaranteed + to exist in all environments that the device must operate. + + See doc/README.link-local for more information. + + - MAC address from environment variables + + FDT_SEQ_MACADDR_FROM_ENV + + Fix-up device tree with MAC addresses fetched sequentially from + environment variables. This config work on assumption that + non-usable ethernet node of device-tree are either not present + or their status has been marked as "disabled". + + - CDP Options: + CONFIG_CDP_DEVICE_ID + + The device id used in CDP trigger frames. + + CONFIG_CDP_DEVICE_ID_PREFIX + + A two character string which is prefixed to the MAC address + of the device. + + CONFIG_CDP_PORT_ID + + A printf format string which contains the ascii name of + the port. Normally is set to "eth%d" which sets + eth0 for the first Ethernet, eth1 for the second etc. + + CONFIG_CDP_CAPABILITIES + + A 32bit integer which indicates the device capabilities; + 0x00000010 for a normal host which does not forwards. + + CONFIG_CDP_VERSION + + An ascii string containing the version of the software. + + CONFIG_CDP_PLATFORM + + An ascii string containing the name of the platform. + + CONFIG_CDP_TRIGGER + + A 32bit integer sent on the trigger. + + CONFIG_CDP_POWER_CONSUMPTION + + A 16bit integer containing the power consumption of the + device in .1 of milliwatts. + + CONFIG_CDP_APPLIANCE_VLAN_TYPE + + A byte containing the id of the VLAN. + +- Status LED: CONFIG_LED_STATUS + + Several configurations allow to display the current + status using a LED. For instance, the LED will blink + fast while running U-Boot code, stop blinking as + soon as a reply to a BOOTP request was received, and + start blinking slow once the Linux kernel is running + (supported by a status LED driver in the Linux + kernel). Defining CONFIG_LED_STATUS enables this + feature in U-Boot. + + Additional options: + + CONFIG_LED_STATUS_GPIO + The status LED can be connected to a GPIO pin. + In such cases, the gpio_led driver can be used as a + status LED backend implementation. Define CONFIG_LED_STATUS_GPIO + to include the gpio_led driver in the U-Boot binary. + + CONFIG_GPIO_LED_INVERTED_TABLE + Some GPIO connected LEDs may have inverted polarity in which + case the GPIO high value corresponds to LED off state and + GPIO low value corresponds to LED on state. + In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined + with a list of GPIO LEDs that have inverted polarity. + +- I2C Support: CONFIG_SYS_I2C + + This enable the NEW i2c subsystem, and will allow you to use + i2c commands at the u-boot command line (as long as you set + CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c + based realtime clock chips or other i2c devices. See + common/cmd_i2c.c for a description of the command line + interface. + + ported i2c driver to the new framework: + - drivers/i2c/soft_i2c.c: + - activate first bus with CONFIG_SYS_I2C_SOFT define + CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE + for defining speed and slave address + - activate second bus with I2C_SOFT_DECLARATIONS2 define + CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2 + for defining speed and slave address + - activate third bus with I2C_SOFT_DECLARATIONS3 define + CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3 + for defining speed and slave address + - activate fourth bus with I2C_SOFT_DECLARATIONS4 define + CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4 + for defining speed and slave address + + - drivers/i2c/fsl_i2c.c: + - activate i2c driver with CONFIG_SYS_I2C_FSL + define CONFIG_SYS_FSL_I2C_OFFSET for setting the register + offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and + CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first + bus. + - If your board supports a second fsl i2c bus, define + CONFIG_SYS_FSL_I2C2_OFFSET for the register offset + CONFIG_SYS_FSL_I2C2_SPEED for the speed and + CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the + second bus. + + - drivers/i2c/tegra_i2c.c: + - activate this driver with CONFIG_SYS_I2C_TEGRA + - This driver adds 4 i2c buses with a fix speed from + 100000 and the slave addr 0! + + - drivers/i2c/ppc4xx_i2c.c + - activate this driver with CONFIG_SYS_I2C_PPC4XX + - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0 + - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1 + + - drivers/i2c/i2c_mxc.c + - activate this driver with CONFIG_SYS_I2C_MXC + - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1 + - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2 + - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3 + - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4 + - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED + - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE + - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED + - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE + - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED + - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE + - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED + - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE + If those defines are not set, default value is 100000 + for speed, and 0 for slave. + + - drivers/i2c/rcar_i2c.c: + - activate this driver with CONFIG_SYS_I2C_RCAR + - This driver adds 4 i2c buses + + - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0 + - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0 + - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1 + - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1 + - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2 + - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2 + - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3 + - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3 + - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses + + - drivers/i2c/sh_i2c.c: + - activate this driver with CONFIG_SYS_I2C_SH + - This driver adds from 2 to 5 i2c buses + + - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0 + - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0 + - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1 + - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1 + - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2 + - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2 + - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3 + - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3 + - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4 + - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4 + - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses + + - drivers/i2c/omap24xx_i2c.c + - activate this driver with CONFIG_SYS_I2C_OMAP24XX + - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0 + - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0 + - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1 + - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1 + - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2 + - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2 + - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3 + - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3 + - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4 + - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4 + + - drivers/i2c/s3c24x0_i2c.c: + - activate this driver with CONFIG_SYS_I2C_S3C24X0 + - This driver adds i2c buses (11 for Exynos5250, Exynos5420 + 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung) + with a fix speed from 100000 and the slave addr 0! + + - drivers/i2c/ihs_i2c.c + - activate this driver with CONFIG_SYS_I2C_IHS + - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0 + - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0 + - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0 + - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1 + - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1 + - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1 + - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2 + - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2 + - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2 + - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3 + - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3 + - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3 + - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL + - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1 + - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1 + - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1 + - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1 + - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1 + - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1 + - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1 + - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1 + + additional defines: + + CONFIG_SYS_NUM_I2C_BUSES + Hold the number of i2c buses you want to use. + + CONFIG_SYS_I2C_DIRECT_BUS + define this, if you don't use i2c muxes on your hardware. + if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can + omit this define. + + CONFIG_SYS_I2C_MAX_HOPS + define how many muxes are maximal consecutively connected + on one i2c bus. If you not use i2c muxes, omit this + define. + + CONFIG_SYS_I2C_BUSES + hold a list of buses you want to use, only used if + CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example + a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and + CONFIG_SYS_NUM_I2C_BUSES = 9: + + CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \ + {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \ + {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \ + {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \ + {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \ + {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \ + {1, {I2C_NULL_HOP}}, \ + {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \ + {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \ + } + + which defines + bus 0 on adapter 0 without a mux + bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1 + bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2 + bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3 + bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4 + bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5 + bus 6 on adapter 1 without a mux + bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1 + bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2 + + If you do not have i2c muxes on your board, omit this define. + +- Legacy I2C Support: + If you use the software i2c interface (CONFIG_SYS_I2C_SOFT) + then the following macros need to be defined (examples are + from include/configs/lwmon.h): + + I2C_INIT + + (Optional). Any commands necessary to enable the I2C + controller or configure ports. + + eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL) + + I2C_ACTIVE + + The code necessary to make the I2C data line active + (driven). If the data line is open collector, this + define can be null. + + eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA) + + I2C_TRISTATE + + The code necessary to make the I2C data line tri-stated + (inactive). If the data line is open collector, this + define can be null. + + eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA) + + I2C_READ + + Code that returns true if the I2C data line is high, + false if it is low. + + eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0) + + I2C_SDA(bit) + + If <bit> is true, sets the I2C data line high. If it + is false, it clears it (low). + + eg: #define I2C_SDA(bit) \ + if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \ + else immr->im_cpm.cp_pbdat &= ~PB_SDA + + I2C_SCL(bit) + + If <bit> is true, sets the I2C clock line high. If it + is false, it clears it (low). + + eg: #define I2C_SCL(bit) \ + if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \ + else immr->im_cpm.cp_pbdat &= ~PB_SCL + + I2C_DELAY + + This delay is invoked four times per clock cycle so this + controls the rate of data transfer. The data rate thus + is 1 / (I2C_DELAY * 4). Often defined to be something + like: + + #define I2C_DELAY udelay(2) + + CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA + + If your arch supports the generic GPIO framework (asm/gpio.h), + then you may alternatively define the two GPIOs that are to be + used as SCL / SDA. Any of the previous I2C_xxx macros will + have GPIO-based defaults assigned to them as appropriate. + + You should define these to the GPIO value as given directly to + the generic GPIO functions. + + CONFIG_SYS_I2C_INIT_BOARD + + When a board is reset during an i2c bus transfer + chips might think that the current transfer is still + in progress. On some boards it is possible to access + the i2c SCLK line directly, either by using the + processor pin as a GPIO or by having a second pin + connected to the bus. If this option is defined a + custom i2c_init_board() routine in boards/xxx/board.c + is run early in the boot sequence. + + CONFIG_I2C_MULTI_BUS + + This option allows the use of multiple I2C buses, each of which + must have a controller. At any point in time, only one bus is + active. To switch to a different bus, use the 'i2c dev' command. + Note that bus numbering is zero-based. + + CONFIG_SYS_I2C_NOPROBES + + This option specifies a list of I2C devices that will be skipped + when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS + is set, specify a list of bus-device pairs. Otherwise, specify + a 1D array of device addresses + + e.g. + #undef CONFIG_I2C_MULTI_BUS + #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68} + + will skip addresses 0x50 and 0x68 on a board with one I2C bus + + #define CONFIG_I2C_MULTI_BUS + #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}} + + will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1 + + CONFIG_SYS_SPD_BUS_NUM + + If defined, then this indicates the I2C bus number for DDR SPD. + If not defined, then U-Boot assumes that SPD is on I2C bus 0. + + CONFIG_SYS_RTC_BUS_NUM + + If defined, then this indicates the I2C bus number for the RTC. + If not defined, then U-Boot assumes that RTC is on I2C bus 0. + + CONFIG_SOFT_I2C_READ_REPEATED_START + + defining this will force the i2c_read() function in + the soft_i2c driver to perform an I2C repeated start + between writing the address pointer and reading the + data. If this define is omitted the default behaviour + of doing a stop-start sequence will be used. Most I2C + devices can use either method, but some require one or + the other. + +- SPI Support: CONFIG_SPI + + Enables SPI driver (so far only tested with + SPI EEPROM, also an instance works with Crystal A/D and + D/As on the SACSng board) + + CONFIG_SOFT_SPI + + Enables a software (bit-bang) SPI driver rather than + using hardware support. This is a general purpose + driver that only requires three general I/O port pins + (two outputs, one input) to function. If this is + defined, the board configuration must define several + SPI configuration items (port pins to use, etc). For + an example, see include/configs/sacsng.h. + + CONFIG_SYS_SPI_MXC_WAIT + Timeout for waiting until spi transfer completed. + default: (CONFIG_SYS_HZ/100) /* 10 ms */ + +- FPGA Support: CONFIG_FPGA + + Enables FPGA subsystem. + + CONFIG_FPGA_<vendor> + + Enables support for specific chip vendors. + (ALTERA, XILINX) + + CONFIG_FPGA_<family> + + Enables support for FPGA family. + (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX) + + CONFIG_FPGA_COUNT + + Specify the number of FPGA devices to support. + + CONFIG_SYS_FPGA_PROG_FEEDBACK + + Enable printing of hash marks during FPGA configuration. + + CONFIG_SYS_FPGA_CHECK_BUSY + + Enable checks on FPGA configuration interface busy + status by the configuration function. This option + will require a board or device specific function to + be written. + + CONFIG_FPGA_DELAY + + If defined, a function that provides delays in the FPGA + configuration driver. + + CONFIG_SYS_FPGA_CHECK_CTRLC + Allow Control-C to interrupt FPGA configuration + + CONFIG_SYS_FPGA_CHECK_ERROR + + Check for configuration errors during FPGA bitfile + loading. For example, abort during Virtex II + configuration if the INIT_B line goes low (which + indicated a CRC error). + + CONFIG_SYS_FPGA_WAIT_INIT + + Maximum time to wait for the INIT_B line to de-assert + after PROB_B has been de-asserted during a Virtex II + FPGA configuration sequence. The default time is 500 + ms. + + CONFIG_SYS_FPGA_WAIT_BUSY + + Maximum time to wait for BUSY to de-assert during + Virtex II FPGA configuration. The default is 5 ms. + + CONFIG_SYS_FPGA_WAIT_CONFIG + + Time to wait after FPGA configuration. The default is + 200 ms. + +- Configuration Management: + + CONFIG_IDENT_STRING + + If defined, this string will be added to the U-Boot + version information (U_BOOT_VERSION) + +- Vendor Parameter Protection: + + U-Boot considers the values of the environment + variables "serial#" (Board Serial Number) and + "ethaddr" (Ethernet Address) to be parameters that + are set once by the board vendor / manufacturer, and + protects these variables from casual modification by + the user. Once set, these variables are read-only, + and write or delete attempts are rejected. You can + change this behaviour: + + If CONFIG_ENV_OVERWRITE is #defined in your config + file, the write protection for vendor parameters is + completely disabled. Anybody can change or delete + these parameters. + + Alternatively, if you define _both_ an ethaddr in the + default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default + Ethernet address is installed in the environment, + which can be changed exactly ONCE by the user. [The + serial# is unaffected by this, i. e. it remains + read-only.] + + The same can be accomplished in a more flexible way + for any variable by configuring the type of access + to allow for those variables in the ".flags" variable + or define CONFIG_ENV_FLAGS_LIST_STATIC. + +- Protected RAM: + CONFIG_PRAM + + Define this variable to enable the reservation of + "protected RAM", i. e. RAM which is not overwritten + by U-Boot. Define CONFIG_PRAM to hold the number of + kB you want to reserve for pRAM. You can overwrite + this default value by defining an environment + variable "pram" to the number of kB you want to + reserve. Note that the board info structure will + still show the full amount of RAM. If pRAM is + reserved, a new environment variable "mem" will + automatically be defined to hold the amount of + remaining RAM in a form that can be passed as boot + argument to Linux, for instance like that: + + setenv bootargs ... mem=\${mem} + saveenv + + This way you can tell Linux not to use this memory, + either, which results in a memory region that will + not be affected by reboots. + + *WARNING* If your board configuration uses automatic + detection of the RAM size, you must make sure that + this memory test is non-destructive. So far, the + following board configurations are known to be + "pRAM-clean": + + IVMS8, IVML24, SPD8xx, + HERMES, IP860, RPXlite, LWMON, + FLAGADM + +- Access to physical memory region (> 4GB) + Some basic support is provided for operations on memory not + normally accessible to U-Boot - e.g. some architectures + support access to more than 4GB of memory on 32-bit + machines using physical address extension or similar. + Define CONFIG_PHYSMEM to access this basic support, which + currently only supports clearing the memory. + +- Error Recovery: + CONFIG_NET_RETRY_COUNT + + This variable defines the number of retries for + network operations like ARP, RARP, TFTP, or BOOTP + before giving up the operation. If not defined, a + default value of 5 is used. + + CONFIG_ARP_TIMEOUT + + Timeout waiting for an ARP reply in milliseconds. + + CONFIG_NFS_TIMEOUT + + Timeout in milliseconds used in NFS protocol. + If you encounter "ERROR: Cannot umount" in nfs command, + try longer timeout such as + #define CONFIG_NFS_TIMEOUT 10000UL + +- Command Interpreter: + CONFIG_SYS_PROMPT_HUSH_PS2 + + This defines the secondary prompt string, which is + printed when the command interpreter needs more input + to complete a command. Usually "> ". + + Note: + + In the current implementation, the local variables + space and global environment variables space are + separated. Local variables are those you define by + simply typing `name=value'. To access a local + variable later on, you have write `$name' or + `${name}'; to execute the contents of a variable + directly type `$name' at the command prompt. + + Global environment variables are those you use + setenv/printenv to work with. To run a command stored + in such a variable, you need to use the run command, + and you must not use the '$' sign to access them. + + To store commands and special characters in a + variable, please use double quotation marks + surrounding the whole text of the variable, instead + of the backslashes before semicolons and special + symbols. + +- Command Line Editing and History: + CONFIG_CMDLINE_PS_SUPPORT + + Enable support for changing the command prompt string + at run-time. Only static string is supported so far. + The string is obtained from environment variables PS1 + and PS2. + +- Default Environment: + CONFIG_EXTRA_ENV_SETTINGS + + Define this to contain any number of null terminated + strings (variable = value pairs) that will be part of + the default environment compiled into the boot image. + + For example, place something like this in your + board's config file: + + #define CONFIG_EXTRA_ENV_SETTINGS \ + "myvar1=value1\0" \ + "myvar2=value2\0" + + Warning: This method is based on knowledge about the + internal format how the environment is stored by the + U-Boot code. This is NOT an official, exported + interface! Although it is unlikely that this format + will change soon, there is no guarantee either. + You better know what you are doing here. + + Note: overly (ab)use of the default environment is + discouraged. Make sure to check other ways to preset + the environment like the "source" command or the + boot command first. + + CONFIG_DELAY_ENVIRONMENT + + Normally the environment is loaded when the board is + initialised so that it is available to U-Boot. This inhibits + that so that the environment is not available until + explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL + this is instead controlled by the value of + /config/load-environment. + +- TFTP Fixed UDP Port: + CONFIG_TFTP_PORT + + If this is defined, the environment variable tftpsrcp + is used to supply the TFTP UDP source port value. + If tftpsrcp isn't defined, the normal pseudo-random port + number generator is used. + + Also, the environment variable tftpdstp is used to supply + the TFTP UDP destination port value. If tftpdstp isn't + defined, the normal port 69 is used. + + The purpose for tftpsrcp is to allow a TFTP server to + blindly start the TFTP transfer using the pre-configured + target IP address and UDP port. This has the effect of + "punching through" the (Windows XP) firewall, allowing + the remainder of the TFTP transfer to proceed normally. + A better solution is to properly configure the firewall, + but sometimes that is not allowed. + +- Show boot progress: + CONFIG_SHOW_BOOT_PROGRESS + + Defining this option allows to add some board- + specific code (calling a user-provided function + "show_boot_progress(int)") that enables you to show + the system's boot progress on some display (for + example, some LED's) on your board. At the moment, + the following checkpoints are implemented: + + +Legacy uImage format: + + Arg Where When + 1 common/cmd_bootm.c before attempting to boot an image + -1 common/cmd_bootm.c Image header has bad magic number + 2 common/cmd_bootm.c Image header has correct magic number + -2 common/cmd_bootm.c Image header has bad checksum + 3 common/cmd_bootm.c Image header has correct checksum + -3 common/cmd_bootm.c Image data has bad checksum + 4 common/cmd_bootm.c Image data has correct checksum + -4 common/cmd_bootm.c Image is for unsupported architecture + 5 common/cmd_bootm.c Architecture check OK + -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi) + 6 common/cmd_bootm.c Image Type check OK + -6 common/cmd_bootm.c gunzip uncompression error + -7 common/cmd_bootm.c Unimplemented compression type + 7 common/cmd_bootm.c Uncompression OK + 8 common/cmd_bootm.c No uncompress/copy overwrite error + -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX) + + 9 common/image.c Start initial ramdisk verification + -10 common/image.c Ramdisk header has bad magic number + -11 common/image.c Ramdisk header has bad checksum + 10 common/image.c Ramdisk header is OK + -12 common/image.c Ramdisk data has bad checksum + 11 common/image.c Ramdisk data has correct checksum + 12 common/image.c Ramdisk verification complete, start loading + -13 common/image.c Wrong Image Type (not PPC Linux ramdisk) + 13 common/image.c Start multifile image verification + 14 common/image.c No initial ramdisk, no multifile, continue. + + 15 arch/<arch>/lib/bootm.c All preparation done, transferring control to OS + + -30 arch/powerpc/lib/board.c Fatal error, hang the system + -31 post/post.c POST test failed, detected by post_output_backlog() + -32 post/post.c POST test failed, detected by post_run_single() + + 34 common/cmd_doc.c before loading a Image from a DOC device + -35 common/cmd_doc.c Bad usage of "doc" command + 35 common/cmd_doc.c correct usage of "doc" command + -36 common/cmd_doc.c No boot device + 36 common/cmd_doc.c correct boot device + -37 common/cmd_doc.c Unknown Chip ID on boot device + 37 common/cmd_doc.c correct chip ID found, device available + -38 common/cmd_doc.c Read Error on boot device + 38 common/cmd_doc.c reading Image header from DOC device OK + -39 common/cmd_doc.c Image header has bad magic number + 39 common/cmd_doc.c Image header has correct magic number + -40 common/cmd_doc.c Error reading Image from DOC device + 40 common/cmd_doc.c Image header has correct magic number + 41 common/cmd_ide.c before loading a Image from a IDE device + -42 common/cmd_ide.c Bad usage of "ide" command + 42 common/cmd_ide.c correct usage of "ide" command + -43 common/cmd_ide.c No boot device + 43 common/cmd_ide.c boot device found + -44 common/cmd_ide.c Device not available + 44 common/cmd_ide.c Device available + -45 common/cmd_ide.c wrong partition selected + 45 common/cmd_ide.c partition selected + -46 common/cmd_ide.c Unknown partition table + 46 common/cmd_ide.c valid partition table found + -47 common/cmd_ide.c Invalid partition type + 47 common/cmd_ide.c correct partition type + -48 common/cmd_ide.c Error reading Image Header on boot device + 48 common/cmd_ide.c reading Image Header from IDE device OK + -49 common/cmd_ide.c Image header has bad magic number + 49 common/cmd_ide.c Image header has correct magic number + -50 common/cmd_ide.c Image header has bad checksum + 50 common/cmd_ide.c Image header has correct checksum + -51 common/cmd_ide.c Error reading Image from IDE device + 51 common/cmd_ide.c reading Image from IDE device OK + 52 common/cmd_nand.c before loading a Image from a NAND device + -53 common/cmd_nand.c Bad usage of "nand" command + 53 common/cmd_nand.c correct usage of "nand" command + -54 common/cmd_nand.c No boot device + 54 common/cmd_nand.c boot device found + -55 common/cmd_nand.c Unknown Chip ID on boot device + 55 common/cmd_nand.c correct chip ID found, device available + -56 common/cmd_nand.c Error reading Image Header on boot device + 56 common/cmd_nand.c reading Image Header from NAND device OK + -57 common/cmd_nand.c Image header has bad magic number + 57 common/cmd_nand.c Image header has correct magic number + -58 common/cmd_nand.c Error reading Image from NAND device + 58 common/cmd_nand.c reading Image from NAND device OK + + -60 common/env_common.c Environment has a bad CRC, using default + + 64 net/eth.c starting with Ethernet configuration. + -64 net/eth.c no Ethernet found. + 65 net/eth.c Ethernet found. + + -80 common/cmd_net.c usage wrong + 80 common/cmd_net.c before calling net_loop() + -81 common/cmd_net.c some error in net_loop() occurred + 81 common/cmd_net.c net_loop() back without error + -82 common/cmd_net.c size == 0 (File with size 0 loaded) + 82 common/cmd_net.c trying automatic boot + 83 common/cmd_net.c running "source" command + -83 common/cmd_net.c some error in automatic boot or "source" command + 84 common/cmd_net.c end without errors + +FIT uImage format: + + Arg Where When + 100 common/cmd_bootm.c Kernel FIT Image has correct format + -100 common/cmd_bootm.c Kernel FIT Image has incorrect format + 101 common/cmd_bootm.c No Kernel subimage unit name, using configuration + -101 common/cmd_bootm.c Can't get configuration for kernel subimage + 102 common/cmd_bootm.c Kernel unit name specified + -103 common/cmd_bootm.c Can't get kernel subimage node offset + 103 common/cmd_bootm.c Found configuration node + 104 common/cmd_bootm.c Got kernel subimage node offset + -104 common/cmd_bootm.c Kernel subimage hash verification failed + 105 common/cmd_bootm.c Kernel subimage hash verification OK + -105 common/cmd_bootm.c Kernel subimage is for unsupported architecture + 106 common/cmd_bootm.c Architecture check OK + -106 common/cmd_bootm.c Kernel subimage has wrong type + 107 common/cmd_bootm.c Kernel subimage type OK + -107 common/cmd_bootm.c Can't get kernel subimage data/size + 108 common/cmd_bootm.c Got kernel subimage data/size + -108 common/cmd_bootm.c Wrong image type (not legacy, FIT) + -109 common/cmd_bootm.c Can't get kernel subimage type + -110 common/cmd_bootm.c Can't get kernel subimage comp + -111 common/cmd_bootm.c Can't get kernel subimage os + -112 common/cmd_bootm.c Can't get kernel subimage load address + -113 common/cmd_bootm.c Image uncompress/copy overwrite error + + 120 common/image.c Start initial ramdisk verification + -120 common/image.c Ramdisk FIT image has incorrect format + 121 common/image.c Ramdisk FIT image has correct format + 122 common/image.c No ramdisk subimage unit name, using configuration + -122 common/image.c Can't get configuration for ramdisk subimage + 123 common/image.c Ramdisk unit name specified + -124 common/image.c Can't get ramdisk subimage node offset + 125 common/image.c Got ramdisk subimage node offset + -125 common/image.c Ramdisk subimage hash verification failed + 126 common/image.c Ramdisk subimage hash verification OK + -126 common/image.c Ramdisk subimage for unsupported architecture + 127 common/image.c Architecture check OK + -127 common/image.c Can't get ramdisk subimage data/size + 128 common/image.c Got ramdisk subimage data/size + 129 common/image.c Can't get ramdisk load address + -129 common/image.c Got ramdisk load address + + -130 common/cmd_doc.c Incorrect FIT image format + 131 common/cmd_doc.c FIT image format OK + + -140 common/cmd_ide.c Incorrect FIT image format + 141 common/cmd_ide.c FIT image format OK + + -150 common/cmd_nand.c Incorrect FIT image format + 151 common/cmd_nand.c FIT image format OK + +- Standalone program support: + CONFIG_STANDALONE_LOAD_ADDR + + This option defines a board specific value for the + address where standalone program gets loaded, thus + overwriting the architecture dependent default + settings. + +- Frame Buffer Address: + CONFIG_FB_ADDR + + Define CONFIG_FB_ADDR if you want to use specific + address for frame buffer. This is typically the case + when using a graphics controller has separate video + memory. U-Boot will then place the frame buffer at + the given address instead of dynamically reserving it + in system RAM by calling lcd_setmem(), which grabs + the memory for the frame buffer depending on the + configured panel size. + + Please see board_init_f function. + +- Automatic software updates via TFTP server + CONFIG_UPDATE_TFTP + CONFIG_UPDATE_TFTP_CNT_MAX + CONFIG_UPDATE_TFTP_MSEC_MAX + + These options enable and control the auto-update feature; + for a more detailed description refer to doc/README.update. + +- MTD Support (mtdparts command, UBI support) + CONFIG_MTD_UBI_WL_THRESHOLD + This parameter defines the maximum difference between the highest + erase counter value and the lowest erase counter value of eraseblocks + of UBI devices. When this threshold is exceeded, UBI starts performing + wear leveling by means of moving data from eraseblock with low erase + counter to eraseblocks with high erase counter. + + The default value should be OK for SLC NAND flashes, NOR flashes and + other flashes which have eraseblock life-cycle 100000 or more. + However, in case of MLC NAND flashes which typically have eraseblock + life-cycle less than 10000, the threshold should be lessened (e.g., + to 128 or 256, although it does not have to be power of 2). + + default: 4096 + + CONFIG_MTD_UBI_BEB_LIMIT + This option specifies the maximum bad physical eraseblocks UBI + expects on the MTD device (per 1024 eraseblocks). If the + underlying flash does not admit of bad eraseblocks (e.g. NOR + flash), this value is ignored. + + NAND datasheets often specify the minimum and maximum NVM + (Number of Valid Blocks) for the flashes' endurance lifetime. + The maximum expected bad eraseblocks per 1024 eraseblocks + then can be calculated as "1024 * (1 - MinNVB / MaxNVB)", + which gives 20 for most NANDs (MaxNVB is basically the total + count of eraseblocks on the chip). + + To put it differently, if this value is 20, UBI will try to + reserve about 1.9% of physical eraseblocks for bad blocks + handling. And that will be 1.9% of eraseblocks on the entire + NAND chip, not just the MTD partition UBI attaches. This means + that if you have, say, a NAND flash chip admits maximum 40 bad + eraseblocks, and it is split on two MTD partitions of the same + size, UBI will reserve 40 eraseblocks when attaching a + partition. + + default: 20 + + CONFIG_MTD_UBI_FASTMAP + Fastmap is a mechanism which allows attaching an UBI device + in nearly constant time. Instead of scanning the whole MTD device it + only has to locate a checkpoint (called fastmap) on the device. + The on-flash fastmap contains all information needed to attach + the device. Using fastmap makes only sense on large devices where + attaching by scanning takes long. UBI will not automatically install + a fastmap on old images, but you can set the UBI parameter + CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note + that fastmap-enabled images are still usable with UBI implementations + without fastmap support. On typical flash devices the whole fastmap + fits into one PEB. UBI will reserve PEBs to hold two fastmaps. + + CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT + Set this parameter to enable fastmap automatically on images + without a fastmap. + default: 0 + + CONFIG_MTD_UBI_FM_DEBUG + Enable UBI fastmap debug + default: 0 + +- SPL framework + CONFIG_SPL + Enable building of SPL globally. + + CONFIG_SPL_LDSCRIPT + LDSCRIPT for linking the SPL binary. + + CONFIG_SPL_MAX_FOOTPRINT + Maximum size in memory allocated to the SPL, BSS included. + When defined, the linker checks that the actual memory + used by SPL from _start to __bss_end does not exceed it. + CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE + must not be both defined at the same time. + + CONFIG_SPL_MAX_SIZE + Maximum size of the SPL image (text, data, rodata, and + linker lists sections), BSS excluded. + When defined, the linker checks that the actual size does + not exceed it. + + CONFIG_SPL_RELOC_TEXT_BASE + Address to relocate to. If unspecified, this is equal to + CONFIG_SPL_TEXT_BASE (i.e. no relocation is done). + + CONFIG_SPL_BSS_START_ADDR + Link address for the BSS within the SPL binary. + + CONFIG_SPL_BSS_MAX_SIZE + Maximum size in memory allocated to the SPL BSS. + When defined, the linker checks that the actual memory used + by SPL from __bss_start to __bss_end does not exceed it. + CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE + must not be both defined at the same time. + + CONFIG_SPL_STACK + Adress of the start of the stack SPL will use + + CONFIG_SPL_PANIC_ON_RAW_IMAGE + When defined, SPL will panic() if the image it has + loaded does not have a signature. + Defining this is useful when code which loads images + in SPL cannot guarantee that absolutely all read errors + will be caught. + An example is the LPC32XX MLC NAND driver, which will + consider that a completely unreadable NAND block is bad, + and thus should be skipped silently. + + CONFIG_SPL_RELOC_STACK + Adress of the start of the stack SPL will use after + relocation. If unspecified, this is equal to + CONFIG_SPL_STACK. + + CONFIG_SYS_SPL_MALLOC_START + Starting address of the malloc pool used in SPL. + When this option is set the full malloc is used in SPL and + it is set up by spl_init() and before that, the simple malloc() + can be used if CONFIG_SYS_MALLOC_F is defined. + + CONFIG_SYS_SPL_MALLOC_SIZE + The size of the malloc pool used in SPL. + + CONFIG_SPL_OS_BOOT + Enable booting directly to an OS from SPL. + See also: doc/README.falcon + + CONFIG_SPL_DISPLAY_PRINT + For ARM, enable an optional function to print more information + about the running system. + + CONFIG_SPL_INIT_MINIMAL + Arch init code should be built for a very small image + + CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION + Partition on the MMC to load U-Boot from when the MMC is being + used in raw mode + + CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR + Sector to load kernel uImage from when MMC is being + used in raw mode (for Falcon mode) + + CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR, + CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS + Sector and number of sectors to load kernel argument + parameters from when MMC is being used in raw mode + (for falcon mode) + + CONFIG_SYS_MMCSD_FS_BOOT_PARTITION + Partition on the MMC to load U-Boot from when the MMC is being + used in fs mode + + CONFIG_SPL_FS_LOAD_PAYLOAD_NAME + Filename to read to load U-Boot when reading from filesystem + + CONFIG_SPL_FS_LOAD_KERNEL_NAME + Filename to read to load kernel uImage when reading + from filesystem (for Falcon mode) + + CONFIG_SPL_FS_LOAD_ARGS_NAME + Filename to read to load kernel argument parameters + when reading from filesystem (for Falcon mode) + + CONFIG_SPL_MPC83XX_WAIT_FOR_NAND + Set this for NAND SPL on PPC mpc83xx targets, so that + start.S waits for the rest of the SPL to load before + continuing (the hardware starts execution after just + loading the first page rather than the full 4K). + + CONFIG_SPL_SKIP_RELOCATE + Avoid SPL relocation + + CONFIG_SPL_NAND_BASE + Include nand_base.c in the SPL. Requires + CONFIG_SPL_NAND_DRIVERS. + + CONFIG_SPL_NAND_DRIVERS + SPL uses normal NAND drivers, not minimal drivers. + + CONFIG_SPL_NAND_IDENT + SPL uses the chip ID list to identify the NAND flash. + Requires CONFIG_SPL_NAND_BASE. + + CONFIG_SPL_NAND_ECC + Include standard software ECC in the SPL + + CONFIG_SPL_NAND_SIMPLE + Support for NAND boot using simple NAND drivers that + expose the cmd_ctrl() interface. + + CONFIG_SPL_UBI + Support for a lightweight UBI (fastmap) scanner and + loader + + CONFIG_SPL_NAND_RAW_ONLY + Support to boot only raw u-boot.bin images. Use this only + if you need to save space. + + CONFIG_SPL_COMMON_INIT_DDR + Set for common ddr init with serial presence detect in + SPL binary. + + CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT, + CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE, + CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS, + CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE, + CONFIG_SYS_NAND_ECCBYTES + Defines the size and behavior of the NAND that SPL uses + to read U-Boot + + CONFIG_SYS_NAND_U_BOOT_OFFS + Location in NAND to read U-Boot from + + CONFIG_SYS_NAND_U_BOOT_DST + Location in memory to load U-Boot to + + CONFIG_SYS_NAND_U_BOOT_SIZE + Size of image to load + + CONFIG_SYS_NAND_U_BOOT_START + Entry point in loaded image to jump to + + CONFIG_SYS_NAND_HW_ECC_OOBFIRST + Define this if you need to first read the OOB and then the + data. This is used, for example, on davinci platforms. + + CONFIG_SPL_RAM_DEVICE + Support for running image already present in ram, in SPL binary + + CONFIG_SPL_PAD_TO + Image offset to which the SPL should be padded before appending + the SPL payload. By default, this is defined as + CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined. + CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL + payload without any padding, or >= CONFIG_SPL_MAX_SIZE. + + CONFIG_SPL_TARGET + Final target image containing SPL and payload. Some SPLs + use an arch-specific makefile fragment instead, for + example if more than one image needs to be produced. + + CONFIG_SPL_FIT_PRINT + Printing information about a FIT image adds quite a bit of + code to SPL. So this is normally disabled in SPL. Use this + option to re-enable it. This will affect the output of the + bootm command when booting a FIT image. + +- TPL framework + CONFIG_TPL + Enable building of TPL globally. + + CONFIG_TPL_PAD_TO + Image offset to which the TPL should be padded before appending + the TPL payload. By default, this is defined as + CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined. + CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL + payload without any padding, or >= CONFIG_SPL_MAX_SIZE. + +- Interrupt support (PPC): + + There are common interrupt_init() and timer_interrupt() + for all PPC archs. interrupt_init() calls interrupt_init_cpu() + for CPU specific initialization. interrupt_init_cpu() + should set decrementer_count to appropriate value. If + CPU resets decrementer automatically after interrupt + (ppc4xx) it should set decrementer_count to zero. + timer_interrupt() calls timer_interrupt_cpu() for CPU + specific handling. If board has watchdog / status_led + / other_activity_monitor it works automatically from + general timer_interrupt(). + + +Board initialization settings: +------------------------------ + +During Initialization u-boot calls a number of board specific functions +to allow the preparation of board specific prerequisites, e.g. pin setup +before drivers are initialized. To enable these callbacks the +following configuration macros have to be defined. Currently this is +architecture specific, so please check arch/your_architecture/lib/board.c +typically in board_init_f() and board_init_r(). + +- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f() +- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r() +- CONFIG_BOARD_LATE_INIT: Call board_late_init() +- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init() + +Configuration Settings: +----------------------- + +- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit. + Optionally it can be defined to support 64-bit memory commands. + +- CONFIG_SYS_LONGHELP: Defined when you want long help messages included; + undefine this when you're short of memory. + +- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default + width of the commands listed in the 'help' command output. + +- CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to + prompt for user input. + +- CONFIG_SYS_CBSIZE: Buffer size for input from the Console + +- CONFIG_SYS_PBSIZE: Buffer size for Console output + +- CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands + +- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to + the application (usually a Linux kernel) when it is + booted + +- CONFIG_SYS_BAUDRATE_TABLE: + List of legal baudrate settings for this board. + +- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END: + Begin and End addresses of the area used by the + simple memory test. + +- CONFIG_SYS_MEMTEST_SCRATCH: + Scratch address used by the alternate memory test + You only need to set this if address zero isn't writeable + +- CONFIG_SYS_MEM_RESERVE_SECURE + Only implemented for ARMv8 for now. + If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory + is substracted from total RAM and won't be reported to OS. + This memory can be used as secure memory. A variable + gd->arch.secure_ram is used to track the location. In systems + the RAM base is not zero, or RAM is divided into banks, + this variable needs to be recalcuated to get the address. + +- CONFIG_SYS_MEM_TOP_HIDE: + If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header, + this specified memory area will get subtracted from the top + (end) of RAM and won't get "touched" at all by U-Boot. By + fixing up gd->ram_size the Linux kernel should gets passed + the now "corrected" memory size and won't touch it either. + This should work for arch/ppc and arch/powerpc. Only Linux + board ports in arch/powerpc with bootwrapper support that + recalculate the memory size from the SDRAM controller setup + will have to get fixed in Linux additionally. + + This option can be used as a workaround for the 440EPx/GRx + CHIP 11 errata where the last 256 bytes in SDRAM shouldn't + be touched. + + WARNING: Please make sure that this value is a multiple of + the Linux page size (normally 4k). If this is not the case, + then the end address of the Linux memory will be located at a + non page size aligned address and this could cause major + problems. + +- CONFIG_SYS_LOADS_BAUD_CHANGE: + Enable temporary baudrate change while serial download + +- CONFIG_SYS_SDRAM_BASE: + Physical start address of SDRAM. _Must_ be 0 here. + +- CONFIG_SYS_FLASH_BASE: + Physical start address of Flash memory. + +- CONFIG_SYS_MONITOR_BASE: + Physical start address of boot monitor code (set by + make config files to be same as the text base address + (CONFIG_SYS_TEXT_BASE) used when linking) - same as + CONFIG_SYS_FLASH_BASE when booting from flash. + +- CONFIG_SYS_MONITOR_LEN: + Size of memory reserved for monitor code, used to + determine _at_compile_time_ (!) if the environment is + embedded within the U-Boot image, or in a separate + flash sector. + +- CONFIG_SYS_MALLOC_LEN: + Size of DRAM reserved for malloc() use. + +- CONFIG_SYS_MALLOC_F_LEN + Size of the malloc() pool for use before relocation. If + this is defined, then a very simple malloc() implementation + will become available before relocation. The address is just + below the global data, and the stack is moved down to make + space. + + This feature allocates regions with increasing addresses + within the region. calloc() is supported, but realloc() + is not available. free() is supported but does nothing. + The memory will be freed (or in fact just forgotten) when + U-Boot relocates itself. + +- CONFIG_SYS_MALLOC_SIMPLE + Provides a simple and small malloc() and calloc() for those + boards which do not use the full malloc in SPL (which is + enabled with CONFIG_SYS_SPL_MALLOC_START). + +- CONFIG_SYS_NONCACHED_MEMORY: + Size of non-cached memory area. This area of memory will be + typically located right below the malloc() area and mapped + uncached in the MMU. This is useful for drivers that would + otherwise require a lot of explicit cache maintenance. For + some drivers it's also impossible to properly maintain the + cache. For example if the regions that need to be flushed + are not a multiple of the cache-line size, *and* padding + cannot be allocated between the regions to align them (i.e. + if the HW requires a contiguous array of regions, and the + size of each region is not cache-aligned), then a flush of + one region may result in overwriting data that hardware has + written to another region in the same cache-line. This can + happen for example in network drivers where descriptors for + buffers are typically smaller than the CPU cache-line (e.g. + 16 bytes vs. 32 or 64 bytes). + + Non-cached memory is only supported on 32-bit ARM at present. + +- CONFIG_SYS_BOOTM_LEN: + Normally compressed uImages are limited to an + uncompressed size of 8 MBytes. If this is not enough, + you can define CONFIG_SYS_BOOTM_LEN in your board config file + to adjust this setting to your needs. + +- CONFIG_SYS_BOOTMAPSZ: + Maximum size of memory mapped by the startup code of + the Linux kernel; all data that must be processed by + the Linux kernel (bd_info, boot arguments, FDT blob if + used) must be put below this limit, unless "bootm_low" + environment variable is defined and non-zero. In such case + all data for the Linux kernel must be between "bootm_low" + and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment + variable "bootm_mapsize" will override the value of + CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined, + then the value in "bootm_size" will be used instead. + +- CONFIG_SYS_BOOT_RAMDISK_HIGH: + Enable initrd_high functionality. If defined then the + initrd_high feature is enabled and the bootm ramdisk subcommand + is enabled. + +- CONFIG_SYS_BOOT_GET_CMDLINE: + Enables allocating and saving kernel cmdline in space between + "bootm_low" and "bootm_low" + BOOTMAPSZ. + +- CONFIG_SYS_BOOT_GET_KBD: + Enables allocating and saving a kernel copy of the bd_info in + space between "bootm_low" and "bootm_low" + BOOTMAPSZ. + +- CONFIG_SYS_MAX_FLASH_BANKS: + Max number of Flash memory banks + +- CONFIG_SYS_MAX_FLASH_SECT: + Max number of sectors on a Flash chip + +- CONFIG_SYS_FLASH_ERASE_TOUT: + Timeout for Flash erase operations (in ms) + +- CONFIG_SYS_FLASH_WRITE_TOUT: + Timeout for Flash write operations (in ms) + +- CONFIG_SYS_FLASH_LOCK_TOUT + Timeout for Flash set sector lock bit operation (in ms) + +- CONFIG_SYS_FLASH_UNLOCK_TOUT + Timeout for Flash clear lock bits operation (in ms) + +- CONFIG_SYS_FLASH_PROTECTION + If defined, hardware flash sectors protection is used + instead of U-Boot software protection. + +- CONFIG_SYS_DIRECT_FLASH_TFTP: + + Enable TFTP transfers directly to flash memory; + without this option such a download has to be + performed in two steps: (1) download to RAM, and (2) + copy from RAM to flash. + + The two-step approach is usually more reliable, since + you can check if the download worked before you erase + the flash, but in some situations (when system RAM is + too limited to allow for a temporary copy of the + downloaded image) this option may be very useful. + +- CONFIG_SYS_FLASH_CFI: + Define if the flash driver uses extra elements in the + common flash structure for storing flash geometry. + +- CONFIG_FLASH_CFI_DRIVER + This option also enables the building of the cfi_flash driver + in the drivers directory + +- CONFIG_FLASH_CFI_MTD + This option enables the building of the cfi_mtd driver + in the drivers directory. The driver exports CFI flash + to the MTD layer. + +- CONFIG_SYS_FLASH_USE_BUFFER_WRITE + Use buffered writes to flash. + +- CONFIG_FLASH_SPANSION_S29WS_N + s29ws-n MirrorBit flash has non-standard addresses for buffered + write commands. + +- CONFIG_SYS_FLASH_QUIET_TEST + If this option is defined, the common CFI flash doesn't + print it's warning upon not recognized FLASH banks. This + is useful, if some of the configured banks are only + optionally available. + +- CONFIG_FLASH_SHOW_PROGRESS + If defined (must be an integer), print out countdown + digits and dots. Recommended value: 45 (9..1) for 80 + column displays, 15 (3..1) for 40 column displays. + +- CONFIG_FLASH_VERIFY + If defined, the content of the flash (destination) is compared + against the source after the write operation. An error message + will be printed when the contents are not identical. + Please note that this option is useless in nearly all cases, + since such flash programming errors usually are detected earlier + while unprotecting/erasing/programming. Please only enable + this option if you really know what you are doing. + +- CONFIG_SYS_RX_ETH_BUFFER: + Defines the number of Ethernet receive buffers. On some + Ethernet controllers it is recommended to set this value + to 8 or even higher (EEPRO100 or 405 EMAC), since all + buffers can be full shortly after enabling the interface + on high Ethernet traffic. + Defaults to 4 if not defined. + +- CONFIG_ENV_MAX_ENTRIES + + Maximum number of entries in the hash table that is used + internally to store the environment settings. The default + setting is supposed to be generous and should work in most + cases. This setting can be used to tune behaviour; see + lib/hashtable.c for details. + +- CONFIG_ENV_FLAGS_LIST_DEFAULT +- CONFIG_ENV_FLAGS_LIST_STATIC + Enable validation of the values given to environment variables when + calling env set. Variables can be restricted to only decimal, + hexadecimal, or boolean. If CONFIG_CMD_NET is also defined, + the variables can also be restricted to IP address or MAC address. + + The format of the list is: + type_attribute = [s|d|x|b|i|m] + access_attribute = [a|r|o|c] + attributes = type_attribute[access_attribute] + entry = variable_name[:attributes] + list = entry[,list] + + The type attributes are: + s - String (default) + d - Decimal + x - Hexadecimal + b - Boolean ([1yYtT|0nNfF]) + i - IP address + m - MAC address + + The access attributes are: + a - Any (default) + r - Read-only + o - Write-once + c - Change-default + + - CONFIG_ENV_FLAGS_LIST_DEFAULT + Define this to a list (string) to define the ".flags" + environment variable in the default or embedded environment. + + - CONFIG_ENV_FLAGS_LIST_STATIC + Define this to a list (string) to define validation that + should be done if an entry is not found in the ".flags" + environment variable. To override a setting in the static + list, simply add an entry for the same variable name to the + ".flags" variable. + + If CONFIG_REGEX is defined, the variable_name above is evaluated as a + regular expression. This allows multiple variables to define the same + flags without explicitly listing them for each variable. + +- CONFIG_ENV_ACCESS_IGNORE_FORCE + If defined, don't allow the -f switch to env set override variable + access flags. + +The following definitions that deal with the placement and management +of environment data (variable area); in general, we support the +following configurations: + +- CONFIG_BUILD_ENVCRC: + + Builds up envcrc with the target environment so that external utils + may easily extract it and embed it in final U-Boot images. + +BE CAREFUL! The first access to the environment happens quite early +in U-Boot initialization (when we try to get the setting of for the +console baudrate). You *MUST* have mapped your NVRAM area then, or +U-Boot will hang. + +Please note that even with NVRAM we still use a copy of the +environment in RAM: we could work on NVRAM directly, but we want to +keep settings there always unmodified except somebody uses "saveenv" +to save the current settings. + +BE CAREFUL! For some special cases, the local device can not use +"saveenv" command. For example, the local device will get the +environment stored in a remote NOR flash by SRIO or PCIE link, +but it can not erase, write this NOR flash by SRIO or PCIE interface. + +- CONFIG_NAND_ENV_DST + + Defines address in RAM to which the nand_spl code should copy the + environment. If redundant environment is used, it will be copied to + CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE. + +Please note that the environment is read-only until the monitor +has been relocated to RAM and a RAM copy of the environment has been +created; also, when using EEPROM you will have to use env_get_f() +until then to read environment variables. + +The environment is protected by a CRC32 checksum. Before the monitor +is relocated into RAM, as a result of a bad CRC you will be working +with the compiled-in default environment - *silently*!!! [This is +necessary, because the first environment variable we need is the +"baudrate" setting for the console - if we have a bad CRC, we don't +have any device yet where we could complain.] + +Note: once the monitor has been relocated, then it will complain if +the default environment is used; a new CRC is computed as soon as you +use the "saveenv" command to store a valid environment. + +- CONFIG_SYS_FAULT_ECHO_LINK_DOWN: + Echo the inverted Ethernet link state to the fault LED. + + Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR + also needs to be defined. + +- CONFIG_SYS_FAULT_MII_ADDR: + MII address of the PHY to check for the Ethernet link state. + +- CONFIG_NS16550_MIN_FUNCTIONS: + Define this if you desire to only have use of the NS16550_init + and NS16550_putc functions for the serial driver located at + drivers/serial/ns16550.c. This option is useful for saving + space for already greatly restricted images, including but not + limited to NAND_SPL configurations. + +- CONFIG_DISPLAY_BOARDINFO + Display information about the board that U-Boot is running on + when U-Boot starts up. The board function checkboard() is called + to do this. + +- CONFIG_DISPLAY_BOARDINFO_LATE + Similar to the previous option, but display this information + later, once stdio is running and output goes to the LCD, if + present. + +- CONFIG_BOARD_SIZE_LIMIT: + Maximum size of the U-Boot image. When defined, the + build system checks that the actual size does not + exceed it. + +Low Level (hardware related) configuration options: +--------------------------------------------------- + +- CONFIG_SYS_CACHELINE_SIZE: + Cache Line Size of the CPU. + +- CONFIG_SYS_CCSRBAR_DEFAULT: + Default (power-on reset) physical address of CCSR on Freescale + PowerPC SOCs. + +- CONFIG_SYS_CCSRBAR: + Virtual address of CCSR. On a 32-bit build, this is typically + the same value as CONFIG_SYS_CCSRBAR_DEFAULT. + +- CONFIG_SYS_CCSRBAR_PHYS: + Physical address of CCSR. CCSR can be relocated to a new + physical address, if desired. In this case, this macro should + be set to that address. Otherwise, it should be set to the + same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR + is typically relocated on 36-bit builds. It is recommended + that this macro be defined via the _HIGH and _LOW macros: + + #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH + * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW) + +- CONFIG_SYS_CCSRBAR_PHYS_HIGH: + Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically + either 0 (32-bit build) or 0xF (36-bit build). This macro is + used in assembly code, so it must not contain typecasts or + integer size suffixes (e.g. "ULL"). + +- CONFIG_SYS_CCSRBAR_PHYS_LOW: + Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is + used in assembly code, so it must not contain typecasts or + integer size suffixes (e.g. "ULL"). + +- CONFIG_SYS_CCSR_DO_NOT_RELOCATE: + If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be + forced to a value that ensures that CCSR is not relocated. + +- Floppy Disk Support: + CONFIG_SYS_FDC_DRIVE_NUMBER + + the default drive number (default value 0) + + CONFIG_SYS_ISA_IO_STRIDE + + defines the spacing between FDC chipset registers + (default value 1) + + CONFIG_SYS_ISA_IO_OFFSET + + defines the offset of register from address. It + depends on which part of the data bus is connected to + the FDC chipset. (default value 0) + + If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and + CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their + default value. + + if CONFIG_SYS_FDC_HW_INIT is defined, then the function + fdc_hw_init() is called at the beginning of the FDC + setup. fdc_hw_init() must be provided by the board + source code. It is used to make hardware-dependent + initializations. + +- CONFIG_IDE_AHB: + Most IDE controllers were designed to be connected with PCI + interface. Only few of them were designed for AHB interface. + When software is doing ATA command and data transfer to + IDE devices through IDE-AHB controller, some additional + registers accessing to these kind of IDE-AHB controller + is required. + +- CONFIG_SYS_IMMR: Physical address of the Internal Memory. + DO NOT CHANGE unless you know exactly what you're + doing! (11-4) [MPC8xx systems only] + +- CONFIG_SYS_INIT_RAM_ADDR: + + Start address of memory area that can be used for + initial data and stack; please note that this must be + writable memory that is working WITHOUT special + initialization, i. e. you CANNOT use normal RAM which + will become available only after programming the + memory controller and running certain initialization + sequences. + + U-Boot uses the following memory types: + - MPC8xx: IMMR (internal memory of the CPU) + +- CONFIG_SYS_GBL_DATA_OFFSET: + + Offset of the initial data structure in the memory + area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually + CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial + data is located at the end of the available space + (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE - + GENERATED_GBL_DATA_SIZE), and the initial stack is just + below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR + + CONFIG_SYS_GBL_DATA_OFFSET) downward. + + Note: + On the MPC824X (or other systems that use the data + cache for initial memory) the address chosen for + CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must + point to an otherwise UNUSED address space between + the top of RAM and the start of the PCI space. + +- CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27) + +- CONFIG_SYS_OR_TIMING_SDRAM: + SDRAM timing + +- CONFIG_SYS_MAMR_PTA: + periodic timer for refresh + +- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM, + CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP, + CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM, + CONFIG_SYS_BR1_PRELIM: + Memory Controller Definitions: BR0/1 and OR0/1 (FLASH) + +- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE, + CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM, + CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM: + Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM) + +- CONFIG_PCI_ENUM_ONLY + Only scan through and get the devices on the buses. + Don't do any setup work, presumably because someone or + something has already done it, and we don't need to do it + a second time. Useful for platforms that are pre-booted + by coreboot or similar. + +- CONFIG_PCI_INDIRECT_BRIDGE: + Enable support for indirect PCI bridges. + +- CONFIG_SYS_SRIO: + Chip has SRIO or not + +- CONFIG_SRIO1: + Board has SRIO 1 port available + +- CONFIG_SRIO2: + Board has SRIO 2 port available + +- CONFIG_SRIO_PCIE_BOOT_MASTER + Board can support master function for Boot from SRIO and PCIE + +- CONFIG_SYS_SRIOn_MEM_VIRT: + Virtual Address of SRIO port 'n' memory region + +- CONFIG_SYS_SRIOn_MEM_PHYS: + Physical Address of SRIO port 'n' memory region + +- CONFIG_SYS_SRIOn_MEM_SIZE: + Size of SRIO port 'n' memory region + +- CONFIG_SYS_NAND_BUSWIDTH_16BIT + Defined to tell the NAND controller that the NAND chip is using + a 16 bit bus. + Not all NAND drivers use this symbol. + Example of drivers that use it: + - drivers/mtd/nand/raw/ndfc.c + - drivers/mtd/nand/raw/mxc_nand.c + +- CONFIG_SYS_NDFC_EBC0_CFG + Sets the EBC0_CFG register for the NDFC. If not defined + a default value will be used. + +- CONFIG_SPD_EEPROM + Get DDR timing information from an I2C EEPROM. Common + with pluggable memory modules such as SODIMMs + + SPD_EEPROM_ADDRESS + I2C address of the SPD EEPROM + +- CONFIG_SYS_SPD_BUS_NUM + If SPD EEPROM is on an I2C bus other than the first + one, specify here. Note that the value must resolve + to something your driver can deal with. + +- CONFIG_SYS_DDR_RAW_TIMING + Get DDR timing information from other than SPD. Common with + soldered DDR chips onboard without SPD. DDR raw timing + parameters are extracted from datasheet and hard-coded into + header files or board specific files. + +- CONFIG_FSL_DDR_INTERACTIVE + Enable interactive DDR debugging. See doc/README.fsl-ddr. + +- CONFIG_FSL_DDR_SYNC_REFRESH + Enable sync of refresh for multiple controllers. + +- CONFIG_FSL_DDR_BIST + Enable built-in memory test for Freescale DDR controllers. + +- CONFIG_SYS_83XX_DDR_USES_CS0 + Only for 83xx systems. If specified, then DDR should + be configured using CS0 and CS1 instead of CS2 and CS3. + +- CONFIG_RMII + Enable RMII mode for all FECs. + Note that this is a global option, we can't + have one FEC in standard MII mode and another in RMII mode. + +- CONFIG_CRC32_VERIFY + Add a verify option to the crc32 command. + The syntax is: + + => crc32 -v <address> <count> <crc32> + + Where address/count indicate a memory area + and crc32 is the correct crc32 which the + area should have. + +- CONFIG_LOOPW + Add the "loopw" memory command. This only takes effect if + the memory commands are activated globally (CONFIG_CMD_MEMORY). + +- CONFIG_MX_CYCLIC + Add the "mdc" and "mwc" memory commands. These are cyclic + "md/mw" commands. + Examples: + + => mdc.b 10 4 500 + This command will print 4 bytes (10,11,12,13) each 500 ms. + + => mwc.l 100 12345678 10 + This command will write 12345678 to address 100 all 10 ms. + + This only takes effect if the memory commands are activated + globally (CONFIG_CMD_MEMORY). + +- CONFIG_SKIP_LOWLEVEL_INIT + [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain + low level initializations (like setting up the memory + controller) are omitted and/or U-Boot does not + relocate itself into RAM. + + Normally this variable MUST NOT be defined. The only + exception is when U-Boot is loaded (to RAM) by some + other boot loader or by a debugger which performs + these initializations itself. + +- CONFIG_SKIP_LOWLEVEL_INIT_ONLY + [ARM926EJ-S only] This allows just the call to lowlevel_init() + to be skipped. The normal CP15 init (such as enabling the + instruction cache) is still performed. + +- CONFIG_SPL_BUILD + Modifies the behaviour of start.S when compiling a loader + that is executed before the actual U-Boot. E.g. when + compiling a NAND SPL. + +- CONFIG_TPL_BUILD + Modifies the behaviour of start.S when compiling a loader + that is executed after the SPL and before the actual U-Boot. + It is loaded by the SPL. + +- CONFIG_SYS_MPC85XX_NO_RESETVEC + Only for 85xx systems. If this variable is specified, the section + .resetvec is not kept and the section .bootpg is placed in the + previous 4k of the .text section. + +- CONFIG_ARCH_MAP_SYSMEM + Generally U-Boot (and in particular the md command) uses + effective address. It is therefore not necessary to regard + U-Boot address as virtual addresses that need to be translated + to physical addresses. However, sandbox requires this, since + it maintains its own little RAM buffer which contains all + addressable memory. This option causes some memory accesses + to be mapped through map_sysmem() / unmap_sysmem(). + +- CONFIG_X86_RESET_VECTOR + If defined, the x86 reset vector code is included. This is not + needed when U-Boot is running from Coreboot. + +- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE + Option to disable subpage write in NAND driver + driver that uses this: + drivers/mtd/nand/raw/davinci_nand.c + +Freescale QE/FMAN Firmware Support: +----------------------------------- + +The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the +loading of "firmware", which is encoded in the QE firmware binary format. +This firmware often needs to be loaded during U-Boot booting, so macros +are used to identify the storage device (NOR flash, SPI, etc) and the address +within that device. + +- CONFIG_SYS_FMAN_FW_ADDR + The address in the storage device where the FMAN microcode is located. The + meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro + is also specified. + +- CONFIG_SYS_QE_FW_ADDR + The address in the storage device where the QE microcode is located. The + meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro + is also specified. + +- CONFIG_SYS_QE_FMAN_FW_LENGTH + The maximum possible size of the firmware. The firmware binary format + has a field that specifies the actual size of the firmware, but it + might not be possible to read any part of the firmware unless some + local storage is allocated to hold the entire firmware first. + +- CONFIG_SYS_QE_FMAN_FW_IN_NOR + Specifies that QE/FMAN firmware is located in NOR flash, mapped as + normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the + virtual address in NOR flash. + +- CONFIG_SYS_QE_FMAN_FW_IN_NAND + Specifies that QE/FMAN firmware is located in NAND flash. + CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash. + +- CONFIG_SYS_QE_FMAN_FW_IN_MMC + Specifies that QE/FMAN firmware is located on the primary SD/MMC + device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device. + +- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE + Specifies that QE/FMAN firmware is located in the remote (master) + memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which + can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound + window->master inbound window->master LAW->the ucode address in + master's memory space. + +Freescale Layerscape Management Complex Firmware Support: +--------------------------------------------------------- +The Freescale Layerscape Management Complex (MC) supports the loading of +"firmware". +This firmware often needs to be loaded during U-Boot booting, so macros +are used to identify the storage device (NOR flash, SPI, etc) and the address +within that device. + +- CONFIG_FSL_MC_ENET + Enable the MC driver for Layerscape SoCs. + +Freescale Layerscape Debug Server Support: +------------------------------------------- +The Freescale Layerscape Debug Server Support supports the loading of +"Debug Server firmware" and triggering SP boot-rom. +This firmware often needs to be loaded during U-Boot booting. + +- CONFIG_SYS_MC_RSV_MEM_ALIGN + Define alignment of reserved memory MC requires + +Reproducible builds +------------------- + +In order to achieve reproducible builds, timestamps used in the U-Boot build +process have to be set to a fixed value. + +This is done using the SOURCE_DATE_EPOCH environment variable. +SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration +option for U-Boot or an environment variable in U-Boot. + +SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC. + +Building the Software: +====================== + +Building U-Boot has been tested in several native build environments +and in many different cross environments. Of course we cannot support +all possibly existing versions of cross development tools in all +(potentially obsolete) versions. In case of tool chain problems we +recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK) +which is extensively used to build and test U-Boot. + +If you are not using a native environment, it is assumed that you +have GNU cross compiling tools available in your path. In this case, +you must set the environment variable CROSS_COMPILE in your shell. +Note that no changes to the Makefile or any other source files are +necessary. For example using the ELDK on a 4xx CPU, please enter: + + $ CROSS_COMPILE=ppc_4xx- + $ export CROSS_COMPILE + +Note: If you wish to generate Windows versions of the utilities in + the tools directory you can use the MinGW toolchain + (http://www.mingw.org). Set your HOST tools to the MinGW + toolchain and execute 'make tools'. For example: + + $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools + + Binaries such as tools/mkimage.exe will be created which can + be executed on computers running Windows. + +U-Boot is intended to be simple to build. After installing the +sources you must configure U-Boot for one specific board type. This +is done by typing: + + make NAME_defconfig + +where "NAME_defconfig" is the name of one of the existing configu- +rations; see boards.cfg for supported names. + +Note: for some board special configuration names may exist; check if + additional information is available from the board vendor; for + instance, the TQM823L systems are available without (standard) + or with LCD support. You can select such additional "features" + when choosing the configuration, i. e. + + make TQM823L_defconfig + - will configure for a plain TQM823L, i. e. no LCD support + + make TQM823L_LCD_defconfig + - will configure for a TQM823L with U-Boot console on LCD + + etc. + + +Finally, type "make all", and you should get some working U-Boot +images ready for download to / installation on your system: + +- "u-boot.bin" is a raw binary image +- "u-boot" is an image in ELF binary format +- "u-boot.srec" is in Motorola S-Record format + +By default the build is performed locally and the objects are saved +in the source directory. One of the two methods can be used to change +this behavior and build U-Boot to some external directory: + +1. Add O= to the make command line invocations: + + make O=/tmp/build distclean + make O=/tmp/build NAME_defconfig + make O=/tmp/build all + +2. Set environment variable KBUILD_OUTPUT to point to the desired location: + + export KBUILD_OUTPUT=/tmp/build + make distclean + make NAME_defconfig + make all + +Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment +variable. + +User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by +setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS. +For example to treat all compiler warnings as errors: + + make KCFLAGS=-Werror + +Please be aware that the Makefiles assume you are using GNU make, so +for instance on NetBSD you might need to use "gmake" instead of +native "make". + + +If the system board that you have is not listed, then you will need +to port U-Boot to your hardware platform. To do this, follow these +steps: + +1. Create a new directory to hold your board specific code. Add any + files you need. In your board directory, you will need at least + the "Makefile" and a "<board>.c". +2. Create a new configuration file "include/configs/<board>.h" for + your board. +3. If you're porting U-Boot to a new CPU, then also create a new + directory to hold your CPU specific code. Add any files you need. +4. Run "make <board>_defconfig" with your new name. +5. Type "make", and you should get a working "u-boot.srec" file + to be installed on your target system. +6. Debug and solve any problems that might arise. + [Of course, this last step is much harder than it sounds.] + + +Testing of U-Boot Modifications, Ports to New Hardware, etc.: +============================================================== + +If you have modified U-Boot sources (for instance added a new board +or support for new devices, a new CPU, etc.) you are expected to +provide feedback to the other developers. The feedback normally takes +the form of a "patch", i. e. a context diff against a certain (latest +official or latest in the git repository) version of U-Boot sources. + +But before you submit such a patch, please verify that your modifi- +cation did not break existing code. At least make sure that *ALL* of +the supported boards compile WITHOUT ANY compiler warnings. To do so, +just run the buildman script (tools/buildman/buildman), which will +configure and build U-Boot for ALL supported system. Be warned, this +will take a while. Please see the buildman README, or run 'buildman -H' +for documentation. + + +See also "U-Boot Porting Guide" below. + + +Monitor Commands - Overview: +============================ + +go - start application at address 'addr' +run - run commands in an environment variable +bootm - boot application image from memory +bootp - boot image via network using BootP/TFTP protocol +bootz - boot zImage from memory +tftpboot- boot image via network using TFTP protocol + and env variables "ipaddr" and "serverip" + (and eventually "gatewayip") +tftpput - upload a file via network using TFTP protocol +rarpboot- boot image via network using RARP/TFTP protocol +diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd' +loads - load S-Record file over serial line +loadb - load binary file over serial line (kermit mode) +md - memory display +mm - memory modify (auto-incrementing) +nm - memory modify (constant address) +mw - memory write (fill) +cp - memory copy +cmp - memory compare +crc32 - checksum calculation +i2c - I2C sub-system +sspi - SPI utility commands +base - print or set address offset +printenv- print environment variables +setenv - set environment variables +saveenv - save environment variables to persistent storage +protect - enable or disable FLASH write protection +erase - erase FLASH memory +flinfo - print FLASH memory information +nand - NAND memory operations (see doc/README.nand) +bdinfo - print Board Info structure +iminfo - print header information for application image +coninfo - print console devices and informations +ide - IDE sub-system +loop - infinite loop on address range +loopw - infinite write loop on address range +mtest - simple RAM test +icache - enable or disable instruction cache +dcache - enable or disable data cache +reset - Perform RESET of the CPU +echo - echo args to console +version - print monitor version +help - print online help +? - alias for 'help' + + +Monitor Commands - Detailed Description: +======================================== + +TODO. + +For now: just type "help <command>". + + +Environment Variables: +====================== + +U-Boot supports user configuration using Environment Variables which +can be made persistent by saving to Flash memory. + +Environment Variables are set using "setenv", printed using +"printenv", and saved to Flash using "saveenv". Using "setenv" +without a value can be used to delete a variable from the +environment. As long as you don't save the environment you are +working with an in-memory copy. In case the Flash area containing the +environment is erased by accident, a default environment is provided. + +Some configuration options can be set using Environment Variables. + +List of environment variables (most likely not complete): + + baudrate - see CONFIG_BAUDRATE + + bootdelay - see CONFIG_BOOTDELAY + + bootcmd - see CONFIG_BOOTCOMMAND + + bootargs - Boot arguments when booting an RTOS image + + bootfile - Name of the image to load with TFTP + + bootm_low - Memory range available for image processing in the bootm + command can be restricted. This variable is given as + a hexadecimal number and defines lowest address allowed + for use by the bootm command. See also "bootm_size" + environment variable. Address defined by "bootm_low" is + also the base of the initial memory mapping for the Linux + kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and + bootm_mapsize. + + bootm_mapsize - Size of the initial memory mapping for the Linux kernel. + This variable is given as a hexadecimal number and it + defines the size of the memory region starting at base + address bootm_low that is accessible by the Linux kernel + during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used + as the default value if it is defined, and bootm_size is + used otherwise. + + bootm_size - Memory range available for image processing in the bootm + command can be restricted. This variable is given as + a hexadecimal number and defines the size of the region + allowed for use by the bootm command. See also "bootm_low" + environment variable. + + updatefile - Location of the software update file on a TFTP server, used + by the automatic software update feature. Please refer to + documentation in doc/README.update for more details. + + autoload - if set to "no" (any string beginning with 'n'), + "bootp" will just load perform a lookup of the + configuration from the BOOTP server, but not try to + load any image using TFTP + + autostart - if set to "yes", an image loaded using the "bootp", + "rarpboot", "tftpboot" or "diskboot" commands will + be automatically started (by internally calling + "bootm") + + If set to "no", a standalone image passed to the + "bootm" command will be copied to the load address + (and eventually uncompressed), but NOT be started. + This can be used to load and uncompress arbitrary + data. + + fdt_high - if set this restricts the maximum address that the + flattened device tree will be copied into upon boot. + For example, if you have a system with 1 GB memory + at physical address 0x10000000, while Linux kernel + only recognizes the first 704 MB as low memory, you + may need to set fdt_high as 0x3C000000 to have the + device tree blob be copied to the maximum address + of the 704 MB low memory, so that Linux kernel can + access it during the boot procedure. + + If this is set to the special value 0xFFFFFFFF then + the fdt will not be copied at all on boot. For this + to work it must reside in writable memory, have + sufficient padding on the end of it for u-boot to + add the information it needs into it, and the memory + must be accessible by the kernel. + + fdtcontroladdr- if set this is the address of the control flattened + device tree used by U-Boot when CONFIG_OF_CONTROL is + defined. + + i2cfast - (PPC405GP|PPC405EP only) + if set to 'y' configures Linux I2C driver for fast + mode (400kHZ). This environment variable is used in + initialization code. So, for changes to be effective + it must be saved and board must be reset. + + initrd_high - restrict positioning of initrd images: + If this variable is not set, initrd images will be + copied to the highest possible address in RAM; this + is usually what you want since it allows for + maximum initrd size. If for some reason you want to + make sure that the initrd image is loaded below the + CONFIG_SYS_BOOTMAPSZ limit, you can set this environment + variable to a value of "no" or "off" or "0". + Alternatively, you can set it to a maximum upper + address to use (U-Boot will still check that it + does not overwrite the U-Boot stack and data). + + For instance, when you have a system with 16 MB + RAM, and want to reserve 4 MB from use by Linux, + you can do this by adding "mem=12M" to the value of + the "bootargs" variable. However, now you must make + sure that the initrd image is placed in the first + 12 MB as well - this can be done with + + setenv initrd_high 00c00000 + + If you set initrd_high to 0xFFFFFFFF, this is an + indication to U-Boot that all addresses are legal + for the Linux kernel, including addresses in flash + memory. In this case U-Boot will NOT COPY the + ramdisk at all. This may be useful to reduce the + boot time on your system, but requires that this + feature is supported by your Linux kernel. + + ipaddr - IP address; needed for tftpboot command + + loadaddr - Default load address for commands like "bootp", + "rarpboot", "tftpboot", "loadb" or "diskboot" + + loads_echo - see CONFIG_LOADS_ECHO + + serverip - TFTP server IP address; needed for tftpboot command + + bootretry - see CONFIG_BOOT_RETRY_TIME + + bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR + + bootstopkey - see CONFIG_AUTOBOOT_STOP_STR + + ethprime - controls which interface is used first. + + ethact - controls which interface is currently active. + For example you can do the following + + => setenv ethact FEC + => ping 192.168.0.1 # traffic sent on FEC + => setenv ethact SCC + => ping 10.0.0.1 # traffic sent on SCC + + ethrotate - When set to "no" U-Boot does not go through all + available network interfaces. + It just stays at the currently selected interface. + + netretry - When set to "no" each network operation will + either succeed or fail without retrying. + When set to "once" the network operation will + fail when all the available network interfaces + are tried once without success. + Useful on scripts which control the retry operation + themselves. + + npe_ucode - set load address for the NPE microcode + + silent_linux - If set then Linux will be told to boot silently, by + changing the console to be empty. If "yes" it will be + made silent. If "no" it will not be made silent. If + unset, then it will be made silent if the U-Boot console + is silent. + + tftpsrcp - If this is set, the value is used for TFTP's + UDP source port. + + tftpdstp - If this is set, the value is used for TFTP's UDP + destination port instead of the Well Know Port 69. + + tftpblocksize - Block size to use for TFTP transfers; if not set, + we use the TFTP server's default block size + + tftptimeout - Retransmission timeout for TFTP packets (in milli- + seconds, minimum value is 1000 = 1 second). Defines + when a packet is considered to be lost so it has to + be retransmitted. The default is 5000 = 5 seconds. + Lowering this value may make downloads succeed + faster in networks with high packet loss rates or + with unreliable TFTP servers. + + tftptimeoutcountmax - maximum count of TFTP timeouts (no + unit, minimum value = 0). Defines how many timeouts + can happen during a single file transfer before that + transfer is aborted. The default is 10, and 0 means + 'no timeouts allowed'. Increasing this value may help + downloads succeed with high packet loss rates, or with + unreliable TFTP servers or client hardware. + + vlan - When set to a value < 4095 the traffic over + Ethernet is encapsulated/received over 802.1q + VLAN tagged frames. + + bootpretryperiod - Period during which BOOTP/DHCP sends retries. + Unsigned value, in milliseconds. If not set, the period will + be either the default (28000), or a value based on + CONFIG_NET_RETRY_COUNT, if defined. This value has + precedence over the valu based on CONFIG_NET_RETRY_COUNT. + +The following image location variables contain the location of images +used in booting. The "Image" column gives the role of the image and is +not an environment variable name. The other columns are environment +variable names. "File Name" gives the name of the file on a TFTP +server, "RAM Address" gives the location in RAM the image will be +loaded to, and "Flash Location" gives the image's address in NOR +flash or offset in NAND flash. + +*Note* - these variables don't have to be defined for all boards, some +boards currently use other variables for these purposes, and some +boards use these variables for other purposes. + +Image File Name RAM Address Flash Location +----- --------- ----------- -------------- +u-boot u-boot u-boot_addr_r u-boot_addr +Linux kernel bootfile kernel_addr_r kernel_addr +device tree blob fdtfile fdt_addr_r fdt_addr +ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr + +The following environment variables may be used and automatically +updated by the network boot commands ("bootp" and "rarpboot"), +depending the information provided by your boot server: + + bootfile - see above + dnsip - IP address of your Domain Name Server + dnsip2 - IP address of your secondary Domain Name Server + gatewayip - IP address of the Gateway (Router) to use + hostname - Target hostname + ipaddr - see above + netmask - Subnet Mask + rootpath - Pathname of the root filesystem on the NFS server + serverip - see above + + +There are two special Environment Variables: + + serial# - contains hardware identification information such + as type string and/or serial number + ethaddr - Ethernet address + +These variables can be set only once (usually during manufacturing of +the board). U-Boot refuses to delete or overwrite these variables +once they have been set once. + + +Further special Environment Variables: + + ver - Contains the U-Boot version string as printed + with the "version" command. This variable is + readonly (see CONFIG_VERSION_VARIABLE). + + +Please note that changes to some configuration parameters may take +only effect after the next boot (yes, that's just like Windoze :-). + + +Callback functions for environment variables: +--------------------------------------------- + +For some environment variables, the behavior of u-boot needs to change +when their values are changed. This functionality allows functions to +be associated with arbitrary variables. On creation, overwrite, or +deletion, the callback will provide the opportunity for some side +effect to happen or for the change to be rejected. + +The callbacks are named and associated with a function using the +U_BOOT_ENV_CALLBACK macro in your board or driver code. + +These callbacks are associated with variables in one of two ways. The +static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC +in the board configuration to a string that defines a list of +associations. The list must be in the following format: + + entry = variable_name[:callback_name] + list = entry[,list] + +If the callback name is not specified, then the callback is deleted. +Spaces are also allowed anywhere in the list. + +Callbacks can also be associated by defining the ".callbacks" variable +with the same list format above. Any association in ".callbacks" will +override any association in the static list. You can define +CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the +".callbacks" environment variable in the default or embedded environment. + +If CONFIG_REGEX is defined, the variable_name above is evaluated as a +regular expression. This allows multiple variables to be connected to +the same callback without explicitly listing them all out. + +The signature of the callback functions is: + + int callback(const char *name, const char *value, enum env_op op, int flags) + +* name - changed environment variable +* value - new value of the environment variable +* op - operation (create, overwrite, or delete) +* flags - attributes of the environment variable change, see flags H_* in + include/search.h + +The return value is 0 if the variable change is accepted and 1 otherwise. + +Command Line Parsing: +===================== + +There are two different command line parsers available with U-Boot: +the old "simple" one, and the much more powerful "hush" shell: + +Old, simple command line parser: +-------------------------------- + +- supports environment variables (through setenv / saveenv commands) +- several commands on one line, separated by ';' +- variable substitution using "... ${name} ..." syntax +- special characters ('$', ';') can be escaped by prefixing with '\', + for example: + setenv bootcmd bootm \${address} +- You can also escape text by enclosing in single apostrophes, for example: + setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off' + +Hush shell: +----------- + +- similar to Bourne shell, with control structures like + if...then...else...fi, for...do...done; while...do...done, + until...do...done, ... +- supports environment ("global") variables (through setenv / saveenv + commands) and local shell variables (through standard shell syntax + "name=value"); only environment variables can be used with "run" + command + +General rules: +-------------- + +(1) If a command line (or an environment variable executed by a "run" + command) contains several commands separated by semicolon, and + one of these commands fails, then the remaining commands will be + executed anyway. + +(2) If you execute several variables with one call to run (i. e. + calling run with a list of variables as arguments), any failing + command will cause "run" to terminate, i. e. the remaining + variables are not executed. + +Note for Redundant Ethernet Interfaces: +======================================= + +Some boards come with redundant Ethernet interfaces; U-Boot supports +such configurations and is capable of automatic selection of a +"working" interface when needed. MAC assignment works as follows: + +Network interfaces are numbered eth0, eth1, eth2, ... Corresponding +MAC addresses can be stored in the environment as "ethaddr" (=>eth0), +"eth1addr" (=>eth1), "eth2addr", ... + +If the network interface stores some valid MAC address (for instance +in SROM), this is used as default address if there is NO correspon- +ding setting in the environment; if the corresponding environment +variable is set, this overrides the settings in the card; that means: + +o If the SROM has a valid MAC address, and there is no address in the + environment, the SROM's address is used. + +o If there is no valid address in the SROM, and a definition in the + environment exists, then the value from the environment variable is + used. + +o If both the SROM and the environment contain a MAC address, and + both addresses are the same, this MAC address is used. + +o If both the SROM and the environment contain a MAC address, and the + addresses differ, the value from the environment is used and a + warning is printed. + +o If neither SROM nor the environment contain a MAC address, an error + is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case + a random, locally-assigned MAC is used. + +If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses +will be programmed into hardware as part of the initialization process. This +may be skipped by setting the appropriate 'ethmacskip' environment variable. +The naming convention is as follows: +"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc. + +Image Formats: +============== + +U-Boot is capable of booting (and performing other auxiliary operations on) +images in two formats: + +New uImage format (FIT) +----------------------- + +Flexible and powerful format based on Flattened Image Tree -- FIT (similar +to Flattened Device Tree). It allows the use of images with multiple +components (several kernels, ramdisks, etc.), with contents protected by +SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory. + + +Old uImage format +----------------- + +Old image format is based on binary files which can be basically anything, +preceded by a special header; see the definitions in include/image.h for +details; basically, the header defines the following image properties: + +* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD, + 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks, + LynxOS, pSOS, QNX, RTEMS, INTEGRITY; + Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS, + INTEGRITY). +* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86, + IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit; + Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC). +* Compression Type (uncompressed, gzip, bzip2) +* Load Address +* Entry Point +* Image Name +* Image Timestamp + +The header is marked by a special Magic Number, and both the header +and the data portions of the image are secured against corruption by +CRC32 checksums. + + +Linux Support: +============== + +Although U-Boot should support any OS or standalone application +easily, the main focus has always been on Linux during the design of +U-Boot. + +U-Boot includes many features that so far have been part of some +special "boot loader" code within the Linux kernel. Also, any +"initrd" images to be used are no longer part of one big Linux image; +instead, kernel and "initrd" are separate images. This implementation +serves several purposes: + +- the same features can be used for other OS or standalone + applications (for instance: using compressed images to reduce the + Flash memory footprint) + +- it becomes much easier to port new Linux kernel versions because + lots of low-level, hardware dependent stuff are done by U-Boot + +- the same Linux kernel image can now be used with different "initrd" + images; of course this also means that different kernel images can + be run with the same "initrd". This makes testing easier (you don't + have to build a new "zImage.initrd" Linux image when you just + change a file in your "initrd"). Also, a field-upgrade of the + software is easier now. + + +Linux HOWTO: +============ + +Porting Linux to U-Boot based systems: +--------------------------------------- + +U-Boot cannot save you from doing all the necessary modifications to +configure the Linux device drivers for use with your target hardware +(no, we don't intend to provide a full virtual machine interface to +Linux :-). + +But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot). + +Just make sure your machine specific header file (for instance +include/asm-ppc/tqm8xx.h) includes the same definition of the Board +Information structure as we define in include/asm-<arch>/u-boot.h, +and make sure that your definition of IMAP_ADDR uses the same value +as your U-Boot configuration in CONFIG_SYS_IMMR. + +Note that U-Boot now has a driver model, a unified model for drivers. +If you are adding a new driver, plumb it into driver model. If there +is no uclass available, you are encouraged to create one. See +doc/driver-model. + + +Configuring the Linux kernel: +----------------------------- + +No specific requirements for U-Boot. Make sure you have some root +device (initial ramdisk, NFS) for your target system. + + +Building a Linux Image: +----------------------- + +With U-Boot, "normal" build targets like "zImage" or "bzImage" are +not used. If you use recent kernel source, a new build target +"uImage" will exist which automatically builds an image usable by +U-Boot. Most older kernels also have support for a "pImage" target, +which was introduced for our predecessor project PPCBoot and uses a +100% compatible format. + +Example: + + make TQM850L_defconfig + make oldconfig + make dep + make uImage + +The "uImage" build target uses a special tool (in 'tools/mkimage') to +encapsulate a compressed Linux kernel image with header information, +CRC32 checksum etc. for use with U-Boot. This is what we are doing: + +* build a standard "vmlinux" kernel image (in ELF binary format): + +* convert the kernel into a raw binary image: + + ${CROSS_COMPILE}-objcopy -O binary \ + -R .note -R .comment \ + -S vmlinux linux.bin + +* compress the binary image: + + gzip -9 linux.bin + +* package compressed binary image for U-Boot: + + mkimage -A ppc -O linux -T kernel -C gzip \ + -a 0 -e 0 -n "Linux Kernel Image" \ + -d linux.bin.gz uImage + + +The "mkimage" tool can also be used to create ramdisk images for use +with U-Boot, either separated from the Linux kernel image, or +combined into one file. "mkimage" encapsulates the images with a 64 +byte header containing information about target architecture, +operating system, image type, compression method, entry points, time +stamp, CRC32 checksums, etc. + +"mkimage" can be called in two ways: to verify existing images and +print the header information, or to build new images. + +In the first form (with "-l" option) mkimage lists the information +contained in the header of an existing U-Boot image; this includes +checksum verification: + + tools/mkimage -l image + -l ==> list image header information + +The second form (with "-d" option) is used to build a U-Boot image +from a "data file" which is used as image payload: + + tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \ + -n name -d data_file image + -A ==> set architecture to 'arch' + -O ==> set operating system to 'os' + -T ==> set image type to 'type' + -C ==> set compression type 'comp' + -a ==> set load address to 'addr' (hex) + -e ==> set entry point to 'ep' (hex) + -n ==> set image name to 'name' + -d ==> use image data from 'datafile' + +Right now, all Linux kernels for PowerPC systems use the same load +address (0x00000000), but the entry point address depends on the +kernel version: + +- 2.2.x kernels have the entry point at 0x0000000C, +- 2.3.x and later kernels have the entry point at 0x00000000. + +So a typical call to build a U-Boot image would read: + + -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ + > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \ + > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \ + > examples/uImage.TQM850L + Image Name: 2.4.4 kernel for TQM850L + Created: Wed Jul 19 02:34:59 2000 + Image Type: PowerPC Linux Kernel Image (gzip compressed) + Data Size: 335725 Bytes = 327.86 kB = 0.32 MB + Load Address: 0x00000000 + Entry Point: 0x00000000 + +To verify the contents of the image (or check for corruption): + + -> tools/mkimage -l examples/uImage.TQM850L + Image Name: 2.4.4 kernel for TQM850L + Created: Wed Jul 19 02:34:59 2000 + Image Type: PowerPC Linux Kernel Image (gzip compressed) + Data Size: 335725 Bytes = 327.86 kB = 0.32 MB + Load Address: 0x00000000 + Entry Point: 0x00000000 + +NOTE: for embedded systems where boot time is critical you can trade +speed for memory and install an UNCOMPRESSED image instead: this +needs more space in Flash, but boots much faster since it does not +need to be uncompressed: + + -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz + -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ + > -A ppc -O linux -T kernel -C none -a 0 -e 0 \ + > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \ + > examples/uImage.TQM850L-uncompressed + Image Name: 2.4.4 kernel for TQM850L + Created: Wed Jul 19 02:34:59 2000 + Image Type: PowerPC Linux Kernel Image (uncompressed) + Data Size: 792160 Bytes = 773.59 kB = 0.76 MB + Load Address: 0x00000000 + Entry Point: 0x00000000 + + +Similar you can build U-Boot images from a 'ramdisk.image.gz' file +when your kernel is intended to use an initial ramdisk: + + -> tools/mkimage -n 'Simple Ramdisk Image' \ + > -A ppc -O linux -T ramdisk -C gzip \ + > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd + Image Name: Simple Ramdisk Image + Created: Wed Jan 12 14:01:50 2000 + Image Type: PowerPC Linux RAMDisk Image (gzip compressed) + Data Size: 566530 Bytes = 553.25 kB = 0.54 MB + Load Address: 0x00000000 + Entry Point: 0x00000000 + +The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i" +option performs the converse operation of the mkimage's second form (the "-d" +option). Given an image built by mkimage, the dumpimage extracts a "data file" +from the image: + + tools/dumpimage -i image -T type -p position data_file + -i ==> extract from the 'image' a specific 'data_file' + -T ==> set image type to 'type' + -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image' + + +Installing a Linux Image: +------------------------- + +To downloading a U-Boot image over the serial (console) interface, +you must convert the image to S-Record format: + + objcopy -I binary -O srec examples/image examples/image.srec + +The 'objcopy' does not understand the information in the U-Boot +image header, so the resulting S-Record file will be relative to +address 0x00000000. To load it to a given address, you need to +specify the target address as 'offset' parameter with the 'loads' +command. + +Example: install the image to address 0x40100000 (which on the +TQM8xxL is in the first Flash bank): + + => erase 40100000 401FFFFF + + .......... done + Erased 8 sectors + + => loads 40100000 + ## Ready for S-Record download ... + ~>examples/image.srec + 1 2 3 4 5 6 7 8 9 10 11 12 13 ... + ... + 15989 15990 15991 15992 + [file transfer complete] + [connected] + ## Start Addr = 0x00000000 + + +You can check the success of the download using the 'iminfo' command; +this includes a checksum verification so you can be sure no data +corruption happened: + + => imi 40100000 + + ## Checking Image at 40100000 ... + Image Name: 2.2.13 for initrd on TQM850L + Image Type: PowerPC Linux Kernel Image (gzip compressed) + Data Size: 335725 Bytes = 327 kB = 0 MB + Load Address: 00000000 + Entry Point: 0000000c + Verifying Checksum ... OK + + +Boot Linux: +----------- + +The "bootm" command is used to boot an application that is stored in +memory (RAM or Flash). In case of a Linux kernel image, the contents +of the "bootargs" environment variable is passed to the kernel as +parameters. You can check and modify this variable using the +"printenv" and "setenv" commands: + + + => printenv bootargs + bootargs=root=/dev/ram + + => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 + + => printenv bootargs + bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 + + => bootm 40020000 + ## Booting Linux kernel at 40020000 ... + Image Name: 2.2.13 for NFS on TQM850L + Image Type: PowerPC Linux Kernel Image (gzip compressed) + Data Size: 381681 Bytes = 372 kB = 0 MB + Load Address: 00000000 + Entry Point: 0000000c + Verifying Checksum ... OK + Uncompressing Kernel Image ... OK + Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000 + Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 + time_init: decrementer frequency = 187500000/60 + Calibrating delay loop... 49.77 BogoMIPS + Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000] + ... + +If you want to boot a Linux kernel with initial RAM disk, you pass +the memory addresses of both the kernel and the initrd image (PPBCOOT +format!) to the "bootm" command: + + => imi 40100000 40200000 + + ## Checking Image at 40100000 ... + Image Name: 2.2.13 for initrd on TQM850L + Image Type: PowerPC Linux Kernel Image (gzip compressed) + Data Size: 335725 Bytes = 327 kB = 0 MB + Load Address: 00000000 + Entry Point: 0000000c + Verifying Checksum ... OK + + ## Checking Image at 40200000 ... + Image Name: Simple Ramdisk Image + Image Type: PowerPC Linux RAMDisk Image (gzip compressed) + Data Size: 566530 Bytes = 553 kB = 0 MB + Load Address: 00000000 + Entry Point: 00000000 + Verifying Checksum ... OK + + => bootm 40100000 40200000 + ## Booting Linux kernel at 40100000 ... + Image Name: 2.2.13 for initrd on TQM850L + Image Type: PowerPC Linux Kernel Image (gzip compressed) + Data Size: 335725 Bytes = 327 kB = 0 MB + Load Address: 00000000 + Entry Point: 0000000c + Verifying Checksum ... OK + Uncompressing Kernel Image ... OK + ## Loading RAMDisk Image at 40200000 ... + Image Name: Simple Ramdisk Image + Image Type: PowerPC Linux RAMDisk Image (gzip compressed) + Data Size: 566530 Bytes = 553 kB = 0 MB + Load Address: 00000000 + Entry Point: 00000000 + Verifying Checksum ... OK + Loading Ramdisk ... OK + Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000 + Boot arguments: root=/dev/ram + time_init: decrementer frequency = 187500000/60 + Calibrating delay loop... 49.77 BogoMIPS + ... + RAMDISK: Compressed image found at block 0 + VFS: Mounted root (ext2 filesystem). + + bash# + +Boot Linux and pass a flat device tree: +----------- + +First, U-Boot must be compiled with the appropriate defines. See the section +titled "Linux Kernel Interface" above for a more in depth explanation. The +following is an example of how to start a kernel and pass an updated +flat device tree: + +=> print oftaddr +oftaddr=0x300000 +=> print oft +oft=oftrees/mpc8540ads.dtb +=> tftp $oftaddr $oft +Speed: 1000, full duplex +Using TSEC0 device +TFTP from server 192.168.1.1; our IP address is 192.168.1.101 +Filename 'oftrees/mpc8540ads.dtb'. +Load address: 0x300000 +Loading: # +done +Bytes transferred = 4106 (100a hex) +=> tftp $loadaddr $bootfile +Speed: 1000, full duplex +Using TSEC0 device +TFTP from server 192.168.1.1; our IP address is 192.168.1.2 +Filename 'uImage'. +Load address: 0x200000 +Loading:############ +done +Bytes transferred = 1029407 (fb51f hex) +=> print loadaddr +loadaddr=200000 +=> print oftaddr +oftaddr=0x300000 +=> bootm $loadaddr - $oftaddr +## Booting image at 00200000 ... + Image Name: Linux-2.6.17-dirty + Image Type: PowerPC Linux Kernel Image (gzip compressed) + Data Size: 1029343 Bytes = 1005.2 kB + Load Address: 00000000 + Entry Point: 00000000 + Verifying Checksum ... OK + Uncompressing Kernel Image ... OK +Booting using flat device tree at 0x300000 +Using MPC85xx ADS machine description +Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb +[snip] + + +More About U-Boot Image Types: +------------------------------ + +U-Boot supports the following image types: + + "Standalone Programs" are directly runnable in the environment + provided by U-Boot; it is expected that (if they behave + well) you can continue to work in U-Boot after return from + the Standalone Program. + "OS Kernel Images" are usually images of some Embedded OS which + will take over control completely. Usually these programs + will install their own set of exception handlers, device + drivers, set up the MMU, etc. - this means, that you cannot + expect to re-enter U-Boot except by resetting the CPU. + "RAMDisk Images" are more or less just data blocks, and their + parameters (address, size) are passed to an OS kernel that is + being started. + "Multi-File Images" contain several images, typically an OS + (Linux) kernel image and one or more data images like + RAMDisks. This construct is useful for instance when you want + to boot over the network using BOOTP etc., where the boot + server provides just a single image file, but you want to get + for instance an OS kernel and a RAMDisk image. + + "Multi-File Images" start with a list of image sizes, each + image size (in bytes) specified by an "uint32_t" in network + byte order. This list is terminated by an "(uint32_t)0". + Immediately after the terminating 0 follow the images, one by + one, all aligned on "uint32_t" boundaries (size rounded up to + a multiple of 4 bytes). + + "Firmware Images" are binary images containing firmware (like + U-Boot or FPGA images) which usually will be programmed to + flash memory. + + "Script files" are command sequences that will be executed by + U-Boot's command interpreter; this feature is especially + useful when you configure U-Boot to use a real shell (hush) + as command interpreter. + +Booting the Linux zImage: +------------------------- + +On some platforms, it's possible to boot Linux zImage. This is done +using the "bootz" command. The syntax of "bootz" command is the same +as the syntax of "bootm" command. + +Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply +kernel with raw initrd images. The syntax is slightly different, the +address of the initrd must be augmented by it's size, in the following +format: "<initrd addres>:<initrd size>". + + +Standalone HOWTO: +================= + +One of the features of U-Boot is that you can dynamically load and +run "standalone" applications, which can use some resources of +U-Boot like console I/O functions or interrupt services. + +Two simple examples are included with the sources: + +"Hello World" Demo: +------------------- + +'examples/hello_world.c' contains a small "Hello World" Demo +application; it is automatically compiled when you build U-Boot. +It's configured to run at address 0x00040004, so you can play with it +like that: + + => loads + ## Ready for S-Record download ... + ~>examples/hello_world.srec + 1 2 3 4 5 6 7 8 9 10 11 ... + [file transfer complete] + [connected] + ## Start Addr = 0x00040004 + + => go 40004 Hello World! This is a test. + ## Starting application at 0x00040004 ... + Hello World + argc = 7 + argv[0] = "40004" + argv[1] = "Hello" + argv[2] = "World!" + argv[3] = "This" + argv[4] = "is" + argv[5] = "a" + argv[6] = "test." + argv[7] = "<NULL>" + Hit any key to exit ... + + ## Application terminated, rc = 0x0 + +Another example, which demonstrates how to register a CPM interrupt +handler with the U-Boot code, can be found in 'examples/timer.c'. +Here, a CPM timer is set up to generate an interrupt every second. +The interrupt service routine is trivial, just printing a '.' +character, but this is just a demo program. The application can be +controlled by the following keys: + + ? - print current values og the CPM Timer registers + b - enable interrupts and start timer + e - stop timer and disable interrupts + q - quit application + + => loads + ## Ready for S-Record download ... + ~>examples/timer.srec + 1 2 3 4 5 6 7 8 9 10 11 ... + [file transfer complete] + [connected] + ## Start Addr = 0x00040004 + + => go 40004 + ## Starting application at 0x00040004 ... + TIMERS=0xfff00980 + Using timer 1 + tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0 + +Hit 'b': + [q, b, e, ?] Set interval 1000000 us + Enabling timer +Hit '?': + [q, b, e, ?] ........ + tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0 +Hit '?': + [q, b, e, ?] . + tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0 +Hit '?': + [q, b, e, ?] . + tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0 +Hit '?': + [q, b, e, ?] . + tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0 +Hit 'e': + [q, b, e, ?] ...Stopping timer +Hit 'q': + [q, b, e, ?] ## Application terminated, rc = 0x0 + + +Minicom warning: +================ + +Over time, many people have reported problems when trying to use the +"minicom" terminal emulation program for serial download. I (wd) +consider minicom to be broken, and recommend not to use it. Under +Unix, I recommend to use C-Kermit for general purpose use (and +especially for kermit binary protocol download ("loadb" command), and +use "cu" for S-Record download ("loads" command). See +http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3. +for help with kermit. + + +Nevertheless, if you absolutely want to use it try adding this +configuration to your "File transfer protocols" section: + + Name Program Name U/D FullScr IO-Red. Multi + X kermit /usr/bin/kermit -i -l %l -s Y U Y N N + Y kermit /usr/bin/kermit -i -l %l -r N D Y N N + + +NetBSD Notes: +============= + +Starting at version 0.9.2, U-Boot supports NetBSD both as host +(build U-Boot) and target system (boots NetBSD/mpc8xx). + +Building requires a cross environment; it is known to work on +NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also +need gmake since the Makefiles are not compatible with BSD make). +Note that the cross-powerpc package does not install include files; +attempting to build U-Boot will fail because <machine/ansi.h> is +missing. This file has to be installed and patched manually: + + # cd /usr/pkg/cross/powerpc-netbsd/include + # mkdir powerpc + # ln -s powerpc machine + # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h + # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST + +Native builds *don't* work due to incompatibilities between native +and U-Boot include files. + +Booting assumes that (the first part of) the image booted is a +stage-2 loader which in turn loads and then invokes the kernel +proper. Loader sources will eventually appear in the NetBSD source +tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the +meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz + + +Implementation Internals: +========================= + +The following is not intended to be a complete description of every +implementation detail. However, it should help to understand the +inner workings of U-Boot and make it easier to port it to custom +hardware. + + +Initial Stack, Global Data: +--------------------------- + +The implementation of U-Boot is complicated by the fact that U-Boot +starts running out of ROM (flash memory), usually without access to +system RAM (because the memory controller is not initialized yet). +This means that we don't have writable Data or BSS segments, and BSS +is not initialized as zero. To be able to get a C environment working +at all, we have to allocate at least a minimal stack. Implementation +options for this are defined and restricted by the CPU used: Some CPU +models provide on-chip memory (like the IMMR area on MPC8xx and +MPC826x processors), on others (parts of) the data cache can be +locked as (mis-) used as memory, etc. + + Chris Hallinan posted a good summary of these issues to the + U-Boot mailing list: + + Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)? + From: "Chris Hallinan" <clh@net1plus.com> + Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET) + ... + + Correct me if I'm wrong, folks, but the way I understand it + is this: Using DCACHE as initial RAM for Stack, etc, does not + require any physical RAM backing up the cache. The cleverness + is that the cache is being used as a temporary supply of + necessary storage before the SDRAM controller is setup. It's + beyond the scope of this list to explain the details, but you + can see how this works by studying the cache architecture and + operation in the architecture and processor-specific manuals. + + OCM is On Chip Memory, which I believe the 405GP has 4K. It + is another option for the system designer to use as an + initial stack/RAM area prior to SDRAM being available. Either + option should work for you. Using CS 4 should be fine if your + board designers haven't used it for something that would + cause you grief during the initial boot! It is frequently not + used. + + CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere + with your processor/board/system design. The default value + you will find in any recent u-boot distribution in + walnut.h should work for you. I'd set it to a value larger + than your SDRAM module. If you have a 64MB SDRAM module, set + it above 400_0000. Just make sure your board has no resources + that are supposed to respond to that address! That code in + start.S has been around a while and should work as is when + you get the config right. + + -Chris Hallinan + DS4.COM, Inc. + +It is essential to remember this, since it has some impact on the C +code for the initialization procedures: + +* Initialized global data (data segment) is read-only. Do not attempt + to write it. + +* Do not use any uninitialized global data (or implicitly initialized + as zero data - BSS segment) at all - this is undefined, initiali- + zation is performed later (when relocating to RAM). + +* Stack space is very limited. Avoid big data buffers or things like + that. + +Having only the stack as writable memory limits means we cannot use +normal global data to share information between the code. But it +turned out that the implementation of U-Boot can be greatly +simplified by making a global data structure (gd_t) available to all +functions. We could pass a pointer to this data as argument to _all_ +functions, but this would bloat the code. Instead we use a feature of +the GCC compiler (Global Register Variables) to share the data: we +place a pointer (gd) to the global data into a register which we +reserve for this purpose. + +When choosing a register for such a purpose we are restricted by the +relevant (E)ABI specifications for the current architecture, and by +GCC's implementation. + +For PowerPC, the following registers have specific use: + R1: stack pointer + R2: reserved for system use + R3-R4: parameter passing and return values + R5-R10: parameter passing + R13: small data area pointer + R30: GOT pointer + R31: frame pointer + + (U-Boot also uses R12 as internal GOT pointer. r12 + is a volatile register so r12 needs to be reset when + going back and forth between asm and C) + + ==> U-Boot will use R2 to hold a pointer to the global data + + Note: on PPC, we could use a static initializer (since the + address of the global data structure is known at compile time), + but it turned out that reserving a register results in somewhat + smaller code - although the code savings are not that big (on + average for all boards 752 bytes for the whole U-Boot image, + 624 text + 127 data). + +On ARM, the following registers are used: + + R0: function argument word/integer result + R1-R3: function argument word + R9: platform specific + R10: stack limit (used only if stack checking is enabled) + R11: argument (frame) pointer + R12: temporary workspace + R13: stack pointer + R14: link register + R15: program counter + + ==> U-Boot will use R9 to hold a pointer to the global data + + Note: on ARM, only R_ARM_RELATIVE relocations are supported. + +On Nios II, the ABI is documented here: + http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf + + ==> U-Boot will use gp to hold a pointer to the global data + + Note: on Nios II, we give "-G0" option to gcc and don't use gp + to access small data sections, so gp is free. + +On NDS32, the following registers are used: + + R0-R1: argument/return + R2-R5: argument + R15: temporary register for assembler + R16: trampoline register + R28: frame pointer (FP) + R29: global pointer (GP) + R30: link register (LP) + R31: stack pointer (SP) + PC: program counter (PC) + + ==> U-Boot will use R10 to hold a pointer to the global data + +NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope, +or current versions of GCC may "optimize" the code too much. + +On RISC-V, the following registers are used: + + x0: hard-wired zero (zero) + x1: return address (ra) + x2: stack pointer (sp) + x3: global pointer (gp) + x4: thread pointer (tp) + x5: link register (t0) + x8: frame pointer (fp) + x10-x11: arguments/return values (a0-1) + x12-x17: arguments (a2-7) + x28-31: temporaries (t3-6) + pc: program counter (pc) + + ==> U-Boot will use gp to hold a pointer to the global data + +Memory Management: +------------------ + +U-Boot runs in system state and uses physical addresses, i.e. the +MMU is not used either for address mapping nor for memory protection. + +The available memory is mapped to fixed addresses using the memory +controller. In this process, a contiguous block is formed for each +memory type (Flash, SDRAM, SRAM), even when it consists of several +physical memory banks. + +U-Boot is installed in the first 128 kB of the first Flash bank (on +TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After +booting and sizing and initializing DRAM, the code relocates itself +to the upper end of DRAM. Immediately below the U-Boot code some +memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN +configuration setting]. Below that, a structure with global Board +Info data is placed, followed by the stack (growing downward). + +Additionally, some exception handler code is copied to the low 8 kB +of DRAM (0x00000000 ... 0x00001FFF). + +So a typical memory configuration with 16 MB of DRAM could look like +this: + + 0x0000 0000 Exception Vector code + : + 0x0000 1FFF + 0x0000 2000 Free for Application Use + : + : + + : + : + 0x00FB FF20 Monitor Stack (Growing downward) + 0x00FB FFAC Board Info Data and permanent copy of global data + 0x00FC 0000 Malloc Arena + : + 0x00FD FFFF + 0x00FE 0000 RAM Copy of Monitor Code + ... eventually: LCD or video framebuffer + ... eventually: pRAM (Protected RAM - unchanged by reset) + 0x00FF FFFF [End of RAM] + + +System Initialization: +---------------------- + +In the reset configuration, U-Boot starts at the reset entry point +(on most PowerPC systems at address 0x00000100). Because of the reset +configuration for CS0# this is a mirror of the on board Flash memory. +To be able to re-map memory U-Boot then jumps to its link address. +To be able to implement the initialization code in C, a (small!) +initial stack is set up in the internal Dual Ported RAM (in case CPUs +which provide such a feature like), or in a locked part of the data +cache. After that, U-Boot initializes the CPU core, the caches and +the SIU. + +Next, all (potentially) available memory banks are mapped using a +preliminary mapping. For example, we put them on 512 MB boundaries +(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash +on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is +programmed for SDRAM access. Using the temporary configuration, a +simple memory test is run that determines the size of the SDRAM +banks. + +When there is more than one SDRAM bank, and the banks are of +different size, the largest is mapped first. For equal size, the first +bank (CS2#) is mapped first. The first mapping is always for address +0x00000000, with any additional banks following immediately to create +contiguous memory starting from 0. + +Then, the monitor installs itself at the upper end of the SDRAM area +and allocates memory for use by malloc() and for the global Board +Info data; also, the exception vector code is copied to the low RAM +pages, and the final stack is set up. + +Only after this relocation will you have a "normal" C environment; +until that you are restricted in several ways, mostly because you are +running from ROM, and because the code will have to be relocated to a +new address in RAM. + + +U-Boot Porting Guide: +---------------------- + +[Based on messages by Jerry Van Baren in the U-Boot-Users mailing +list, October 2002] + + +int main(int argc, char *argv[]) +{ + sighandler_t no_more_time; + + signal(SIGALRM, no_more_time); + alarm(PROJECT_DEADLINE - toSec (3 * WEEK)); + + if (available_money > available_manpower) { + Pay consultant to port U-Boot; + return 0; + } + + Download latest U-Boot source; + + Subscribe to u-boot mailing list; + + if (clueless) + email("Hi, I am new to U-Boot, how do I get started?"); + + while (learning) { + Read the README file in the top level directory; + Read http://www.denx.de/twiki/bin/view/DULG/Manual; + Read applicable doc/*.README; + Read the source, Luke; + /* find . -name "*.[chS]" | xargs grep -i <keyword> */ + } + + if (available_money > toLocalCurrency ($2500)) + Buy a BDI3000; + else + Add a lot of aggravation and time; + + if (a similar board exists) { /* hopefully... */ + cp -a board/<similar> board/<myboard> + cp include/configs/<similar>.h include/configs/<myboard>.h + } else { + Create your own board support subdirectory; + Create your own board include/configs/<myboard>.h file; + } + Edit new board/<myboard> files + Edit new include/configs/<myboard>.h + + while (!accepted) { + while (!running) { + do { + Add / modify source code; + } until (compiles); + Debug; + if (clueless) + email("Hi, I am having problems..."); + } + Send patch file to the U-Boot email list; + if (reasonable critiques) + Incorporate improvements from email list code review; + else + Defend code as written; + } + + return 0; +} + +void no_more_time (int sig) +{ + hire_a_guru(); +} + + +Coding Standards: +----------------- + +All contributions to U-Boot should conform to the Linux kernel +coding style; see the kernel coding style guide at +https://www.kernel.org/doc/html/latest/process/coding-style.html, and the +script "scripts/Lindent" in your Linux kernel source directory. + +Source files originating from a different project (for example the +MTD subsystem) are generally exempt from these guidelines and are not +reformatted to ease subsequent migration to newer versions of those +sources. + +Please note that U-Boot is implemented in C (and to some small parts in +Assembler); no C++ is used, so please do not use C++ style comments (//) +in your code. + +Please also stick to the following formatting rules: +- remove any trailing white space +- use TAB characters for indentation and vertical alignment, not spaces +- make sure NOT to use DOS '\r\n' line feeds +- do not add more than 2 consecutive empty lines to source files +- do not add trailing empty lines to source files + +Submissions which do not conform to the standards may be returned +with a request to reformat the changes. + + +Submitting Patches: +------------------- + +Since the number of patches for U-Boot is growing, we need to +establish some rules. Submissions which do not conform to these rules +may be rejected, even when they contain important and valuable stuff. + +Please see http://www.denx.de/wiki/U-Boot/Patches for details. + +Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>; +see https://lists.denx.de/listinfo/u-boot + +When you send a patch, please include the following information with +it: + +* For bug fixes: a description of the bug and how your patch fixes + this bug. Please try to include a way of demonstrating that the + patch actually fixes something. + +* For new features: a description of the feature and your + implementation. + +* A CHANGELOG entry as plaintext (separate from the patch) + +* For major contributions, add a MAINTAINERS file with your + information and associated file and directory references. + +* When you add support for a new board, don't forget to add a + maintainer e-mail address to the boards.cfg file, too. + +* If your patch adds new configuration options, don't forget to + document these in the README file. + +* The patch itself. If you are using git (which is *strongly* + recommended) you can easily generate the patch using the + "git format-patch". If you then use "git send-email" to send it to + the U-Boot mailing list, you will avoid most of the common problems + with some other mail clients. + + If you cannot use git, use "diff -purN OLD NEW". If your version of + diff does not support these options, then get the latest version of + GNU diff. + + The current directory when running this command shall be the parent + directory of the U-Boot source tree (i. e. please make sure that + your patch includes sufficient directory information for the + affected files). + + We prefer patches as plain text. MIME attachments are discouraged, + and compressed attachments must not be used. + +* If one logical set of modifications affects or creates several + files, all these changes shall be submitted in a SINGLE patch file. + +* Changesets that contain different, unrelated modifications shall be + submitted as SEPARATE patches, one patch per changeset. + + +Notes: + +* Before sending the patch, run the buildman script on your patched + source tree and make sure that no errors or warnings are reported + for any of the boards. + +* Keep your modifications to the necessary minimum: A patch + containing several unrelated changes or arbitrary reformats will be + returned with a request to re-formatting / split it. + +* If you modify existing code, make sure that your new code does not + add to the memory footprint of the code ;-) Small is beautiful! + When adding new features, these should compile conditionally only + (using #ifdef), and the resulting code with the new feature + disabled must not need more memory than the old code without your + modification. + +* Remember that there is a size limit of 100 kB per message on the + u-boot mailing list. Bigger patches will be moderated. If they are + reasonable and not too big, they will be acknowledged. But patches + bigger than the size limit should be avoided. |