kbuild: introduce ccflags-y, asflags-y and ldflags-y
Introduce ccflags-y, asflags-y and ldflags-y so we soon can
deprecate use of EXTRA_CFLAGS, EXTRA_AFLAGS and EXTRA_LDFLAGS.
This patch does not touch any in-tree users - thats next round.
Lets get this committed first and then fix the users of the
soon to be deprecated variants next.
The rationale behind this change is to introduce support for
makefile fragments like:
ccflags-$(CONFIG_WHATEVER_DEBUG) := -DDEBUG
As a replacement for the uglier:
ifeq ($(CONFIG_WHATEVER_DEBUG),y)
EXTRA_CFLAGS := -DDEBUG
endif
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 08fbe6c..f099b81 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -276,40 +276,39 @@
--- 3.7 Compilation flags
- EXTRA_CFLAGS, EXTRA_AFLAGS, EXTRA_LDFLAGS
+ 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.
+ 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.
- All the EXTRA_ variables apply only to the kbuild makefile
- where they are assigned. The EXTRA_ variables apply to all
- commands executed in the kbuild makefile.
-
- $(EXTRA_CFLAGS) specifies options for compiling C files with
- $(CC).
+ ccflags-y specifies options for compiling C files with $(CC).
Example:
# drivers/sound/emu10k1/Makefile
- EXTRA_CFLAGS += -I$(obj)
- ifdef DEBUG
- EXTRA_CFLAGS += -DEMU10K1_DEBUG
- endif
+ ccflags-y += -I$(obj)
+ ccflags-$(DEBUG) += -DEMU10K1_DEBUG
This variable is necessary because the top Makefile owns the
variable $(KBUILD_CFLAGS) and uses it for compilation flags for the
entire tree.
- $(EXTRA_AFLAGS) is a similar string for per-directory options
+ asflags-y is a similar string for per-directory options
when compiling assembly language source.
Example:
#arch/x86_64/kernel/Makefile
- EXTRA_AFLAGS := -traditional
+ asflags-y := -traditional
- $(EXTRA_LDFLAGS) is a string for per-directory options to $(LD).
+ ldflags-y is a string for per-directory options to $(LD).
Example:
#arch/m68k/fpsp040/Makefile
- EXTRA_LDFLAGS := -x
+ ldflags-y := -x
CFLAGS_$@, AFLAGS_$@
@@ -495,9 +494,9 @@
Example:
#fs/reiserfs/Makefile
- EXTRA_CFLAGS := $(call cc-ifversion, -lt, 0402, -O1)
+ ccflags-y := $(call cc-ifversion, -lt, 0402, -O1)
- In this example, EXTRA_CFLAGS will be assigned the value -O1 if the
+ In this example, ccflags-y will be assigned the value -O1 if the
$(CC) version is less than 4.2.
cc-ifversion takes all the shell operators:
-eq, -ne, -lt, -le, -gt, and -ge
@@ -783,7 +782,7 @@
Example:
#arch/s390/Makefile
LDFLAGS := -m elf_s390
- Note: EXTRA_LDFLAGS can be used to further customise
+ Note: ldflags-y can be used to further customise
the flags used. See chapter 3.7.
LDFLAGS_MODULE Options for $(LD) when linking modules
@@ -1100,7 +1099,7 @@
When building the *.lds target, kbuild uses the variables:
KBUILD_CPPFLAGS : Set in top-level Makefile
- EXTRA_CPPFLAGS : May be set in the kbuild makefile
+ cppflags-y : May be set in the kbuild makefile
CPPFLAGS_$(@F) : Target specific flags.
Note that the full filename is used in this
assignment.