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Commit eb07e1b4 authored by Matt Mooney's avatar Matt Mooney Committed by Linus Torvalds
Browse files

Documentation: update kbuild make typos/grammar/text flow 



Update section 3.7 examples to reflect the current state of the
Makefiles used. Fix spelling and grammar errors along with flow of text.

Signed-off-by: default avatarmatt mooney <mfm@muteddisk.com>
Reviewed-by: default avatarWANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2f5a2f81

Documentation/kbuild/makefiles.txt

+25 −28
Original line number Diff line number Diff line
@@ -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