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Diffstat (limited to 'Documentation/kbuild/makefiles.txt')
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 53 |
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 |