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-rw-r--r--Documentation/kbuild/makefiles.txt53
1 files changed, 25 insertions, 28 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index d77e24e0055..31bfcbf958f 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -285,45 +285,42 @@ more details, with real examples.
--- 3.7 Compilation flags
ccflags-y, asflags-y and ldflags-y
- The three flags listed above applies only to the kbuild makefile
- where they are assigned. They are used for all the normal
- cc, as and ld invocation happenign during a recursive build.
+ The three flags listed above apply only to the kbuild makefile where
+ they are assigned (i.e., per-directory). They are used for all the
+ normal cc, as and ld invocation happening during a recursive build.
Note: Flags with the same behaviour were previously named:
- EXTRA_CFLAGS, EXTRA_AFLAGS and EXTRA_LDFLAGS.
- They are yet supported but their use are deprecated.
+ EXTRA_CFLAGS, EXTRA_AFLAGS and EXTRA_LDFLAGS. They are still
+ supported but their use is deprecated.
- ccflags-y specifies options for compiling C files with $(CC).
+ ccflags-y specifies options for compiling with $(CC).
Example:
- # drivers/sound/emu10k1/Makefile
- ccflags-y += -I$(obj)
- ccflags-$(DEBUG) += -DEMU10K1_DEBUG
-
+ # drivers/acpi/Makefile
+ ccflags-y := -Os
+ ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT
This variable is necessary because the top Makefile owns the
variable $(KBUILD_CFLAGS) and uses it for compilation flags for the
entire tree.
- asflags-y is a similar string for per-directory options
- when compiling assembly language source.
+ asflags-y specifies options for assembling with $(AS).
Example:
- #arch/x86_64/kernel/Makefile
- asflags-y := -traditional
-
+ #arch/sparc/kernel/Makefile
+ asflags-y := -ansi
- ldflags-y is a string for per-directory options to $(LD).
+ ldflags-y specifies options for linking with $(LD).
Example:
- #arch/m68k/fpsp040/Makefile
- ldflags-y := -x
+ #arch/cris/boot/compressed/Makefile
+ ldflags-y += -T $(srctree)/$(src)/decompress_$(arch-y).lds
subdir-ccflags-y, subdir-asflags-y
- The two flags listed above are similar to ccflags-y and as-falgs-y.
- The difference is that the subdir- variants has effect for the kbuild
- file where tey are present and all subdirectories.
- Options specified using subdir-* are added to the commandline before
- the options specified using the non-subdir variants.
+ The two flags listed above are similar to ccflags-y and asflags-y.
+ The difference is that the subdir- variants affect the kbuild
+ file where they are present and all subdirectories. Options specified
+ using subdir-* are added to the commandline before the options
+ specified using the non-subdir variants.
Example:
subdir-ccflags-y := -Werror
@@ -341,18 +338,18 @@ more details, with real examples.
CFLAGS_aha152x.o = -DAHA152X_STAT -DAUTOCONF
CFLAGS_gdth.o = # -DDEBUG_GDTH=2 -D__SERIAL__ -D__COM2__ \
-DGDTH_STATISTICS
- CFLAGS_seagate.o = -DARBITRATE -DPARITY -DSEAGATE_USE_ASM
- These three lines specify compilation flags for aha152x.o,
- gdth.o, and seagate.o
+ These two lines specify compilation flags for aha152x.o and gdth.o.
$(AFLAGS_$@) is a similar feature for source files in assembly
languages.
Example:
# arch/arm/kernel/Makefile
- AFLAGS_head-armv.o := -DTEXTADDR=$(TEXTADDR) -traditional
- AFLAGS_head-armo.o := -DTEXTADDR=$(TEXTADDR) -traditional
+ AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
+ AFLAGS_crunch-bits.o := -Wa,-mcpu=ep9312
+ AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
+
--- 3.9 Dependency tracking