--- 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_$@
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
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 $(LD) when linking modules
When building the *.lds target, kbuild uses the variables:
KBUILD_CPPFLAGS : Set in top-level Makefile
- EXTRA_CPPFLAGS : May be set in the kbuild makefile
+ cppflags-y : May be set in the kbuild makefile
CPPFLAGS_$(@F) : Target specific flags.
Note that the full filename is used in this
assignment.
+# Backward compatibility
+asflags-y += $(EXTRA_AFLAGS)
+ccflags-y += $(EXTRA_CFLAGS)
+cppflags-y += $(EXTRA_CPPFLAGS)
+ldflags-y += $(EXTRA_LDFLAGS)
+
# Figure out what we need to build from the various variables
# ===========================================================================
modname_flags = $(if $(filter 1,$(words $(modname))),\
-D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")
-_c_flags = $(KBUILD_CFLAGS) $(EXTRA_CFLAGS) $(CFLAGS_$(basetarget).o)
-_a_flags = $(KBUILD_AFLAGS) $(EXTRA_AFLAGS) $(AFLAGS_$(basetarget).o)
-_cpp_flags = $(KBUILD_CPPFLAGS) $(EXTRA_CPPFLAGS) $(CPPFLAGS_$(@F))
+_c_flags = $(KBUILD_CFLAGS) $(ccflags-y) $(CFLAGS_$(basetarget).o)
+_a_flags = $(KBUILD_AFLAGS) $(asflags-y) $(AFLAGS_$(basetarget).o)
+_cpp_flags = $(KBUILD_CPPFLAGS) $(cppflags-y) $(CPPFLAGS_$(@F))
# If building the kernel in a separate objtree expand all occurrences
# of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').
cpp_flags = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(__cpp_flags)
-ld_flags = $(LDFLAGS) $(EXTRA_LDFLAGS)
+ld_flags = $(LDFLAGS) $(ldflags-y)
# Finds the multi-part object the current object will be linked into
modname-multi = $(sort $(foreach m,$(multi-used),\
# ---------------------------------------------------------------------------
quiet_cmd_ld = LD $@
-cmd_ld = $(LD) $(LDFLAGS) $(EXTRA_LDFLAGS) $(LDFLAGS_$(@F)) \
+cmd_ld = $(LD) $(LDFLAGS) $(ldflags-y) $(LDFLAGS_$(@F)) \
$(filter-out FORCE,$^) -o $@
# Objcopy