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# Kconfig - kernel configuration options
#
# Copyright (c) 2014-2015 Wind River Systems, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
choice
prompt "Kernel Type"
default MICROKERNEL
config NANOKERNEL
bool "Nano Kernel"
config MICROKERNEL
bool "Micro Kernel"
endchoice
menu "General Kernel Options"
config SYS_CLOCK_TICKS_PER_SEC
int
prompt "System tick frequency (in ticks/second)"
default 100
help
This option specifies the frequency of the system clock in Hz.
config SYS_CLOCK_HW_CYCLES_PER_SEC
int "System clock's h/w timer frequency"
help
This option specifies the frequency of the hardware timer used for the
system clock (in Hz). This option is set by the platform's Kconfig file
and the user should generally avoid modifying it via the menu configuration.
config SYS_CLOCK_EXISTS
bool
# omit prompt to signify a "hidden" option
default n if (SYS_CLOCK_TICKS_PER_SEC = 0)
default y
help
This option specifies that the kernel lacks timer support.
config INIT_STACKS
bool
prompt "Initialize stack areas"
default n
help
This option instructs the kernel to initialize stack areas with a
known value (0xaa) before they are first used, so that the high
water mark can be easily determined. This applies to the stack areas
for both tasks and fibers, as well as for the microkernel server's command
stack.
config XIP
bool
prompt "Execute in place"
help
This option allows the kernel to operate with its text and read-only
sections residing in ROM (or similar read-only memory). Not all platforms
support this option so it must be used with care; you must also
supply a linker command file when building your image. Enabling this
option increases both the code and data footprint of the image.
config RING_BUFFER
bool
prompt "Enable ring buffers"
default n
help
Enable usage of ring buffers. Similar to nanokernel FIFOs but manage
their own buffer memory and can store arbitrary data. For optimal
performance, use buffer sizes that are a power of 2.
config EVENT_LOGGER
bool
prompt "Enable event logger"
default n
select RING_BUFFER
help
Enable event logging feature. Allow the usage of a ring buffer to
transmit event messages with a single interface to collect them.
config KERNEL_EVENT_LOGGER
bool
prompt "Enable kernel event logger features"
default n
select EVENT_LOGGER
help
This feature enables the usage of the profiling logger. Provides the
logging of sleep events (either entering or leaving low power conditions),
context switch events, interrupt events, boot events and a method to
collect these event messages.
config KERNEL_EVENT_LOGGER_BUFFER_SIZE
int
prompt "Kernel event logger buffer size"
default 128
depends on KERNEL_EVENT_LOGGER
help
Buffer size in 32-bit words.
config KERNEL_INIT_PRIORITY_DEFAULT
int
prompt "Default init priority"
help
Defaut minimal init priority for each init level.
config KERNEL_INIT_PRIORITY_DEVICE
int
prompt "Default init priority for device drivers"
help
Device driver, that depends on common components, such as
interrupt controller, but does not depend on other devices,
uses this init priority.
menu "Kernel event logging points"
depends on KERNEL_EVENT_LOGGER
config KERNEL_EVENT_LOGGER_CONTEXT_SWITCH
bool
prompt "Context switch event logging point"
default n
depends on KERNEL_EVENT_LOGGER
help
Enable the context switch event messages.
config KERNEL_EVENT_LOGGER_INTERRUPT
bool
prompt "Interrupt event logging point"
default n
depends on KERNEL_EVENT_LOGGER
help
Enable interrupt event messages. These messages provide the following
information: The time when interrupts occur.
config KERNEL_EVENT_LOGGER_SLEEP
bool
prompt "Sleep event logging point"
default n
depends on KERNEL_EVENT_LOGGER && ((MICROKERNEL && ADVANCED_POWER_MANAGEMENT) || NANOKERNEL)
help
Enable low power condition event messages. These messages provide the
following information:
- When the CPU went to sleep mode.
- When the CPU woke up.
- The ID of the interrupt that woke the CPU up.
endmenu
menu "Security Options"
config STACK_CANARIES
bool
prompt "Compiler stack canaries"
default n
help
This option enables compiler stack canaries support kernel functions.
If stack canaries are supported by the compiler, it will emit
extra code that inserts a canary value into the stack frame when
a function is entered and validates this value upon exit.
Stack corruption (such as that caused by buffer overflow) results
in a fatal error condition for the running entity.
Enabling this option can result in a significant increase
in footprint and an associated decrease in performance.
If stack canaries are not supported by the compiler, enabling this
option has no effect.
endmenu
endmenu
source "kernel/nanokernel/Kconfig"
config ADVANCED_POWER_MANAGEMENT
bool
prompt "Advanced power management"
default n
help
This option enables the platform to implement extra power management
policies whenever the kernel becomes idle. The kernel invokes
_sys_power_save_idle() to inform the power management subsystem of the
number of ticks until the next kernel timer is due to expire.
menu "Advanced Power Management Features"
depends on ADVANCED_POWER_MANAGEMENT
config ADVANCED_IDLE
bool
prompt "Advanced idle state"
default n
depends on MICROKERNEL && ADVANCED_POWER_MANAGEMENT && ADVANCED_IDLE_SUPPORTED
help
This option enables the kernel to interface to a custom advanced idle
power saving manager. This permits the system to enter a custom
power saving state when the kernel becomes idle for extended periods,
and then to restore the system to its previous state (rather than
booting up from scratch) when the kernel is re-activated.
config ADV_IDLE_STACK_SIZE
int
prompt "Advanced idle state stack size"
default 16
depends on ADVANCED_IDLE
help
This option defines the size of the separate stack used during the
system state check while the booting up. A separate stack is used
to avoid memory corruption on the system re-activation from power
down mode. The stack size must be large enough to hold the return
address (4 bytes) and the _AdvIdleCheckSleep() stack frame.
config TICKLESS_IDLE
bool
prompt "Tickless idle"
default y
depends on MICROKERNEL || NANOKERNEL_TICKLESS_IDLE_SUPPORTED
help
This option suppresses periodic system clock interrupts whenever the
kernel becomes idle. This permits the system to remain in a power
saving state for extended periods without having to wake up to
service each tick as it occurs.
As a policy, an architecture should always provide support for tickless in
the microkernel. If an architecture also provides support for nanokernel
systems, it must select the NANOKERNEL_TICKLESS_IDLE_SUPPORTED kconfig
option.
config TICKLESS_IDLE_THRESH
int
prompt "Tickless idle threshold"
default 3
depends on TICKLESS_IDLE
help
This option enables clock interrupt suppression when the kernel idles
for only a short period of time. It specifies the minimum number of
ticks that must occur before the next kernel timer expires in order
for suppression to happen.
endmenu
if MICROKERNEL
source "kernel/microkernel/Kconfig"
endif
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