kbuild: allow assignment to {A,C,LD}FLAGS_MODULE on the command line

It is now possible to assign options to AS, CC and LD
on the command line - which is only used when building modules.

{A,C,LD}FLAGS_MODULE was all used both in the top-level Makefile
in the arch makefiles, thus users had no way to specify
additional options to AS, CC, LD when building modules
without overriding the original value.

Introduce a new set of variables KBUILD_{A,C,LD}FLAGS_MODULE
that is used by arch specific files and free up
{A,C,LD}FLAGS_MODULE so they can be assigned on
the command line.

All arch Makefiles that used the old variables has been updated.

Note: Previously we had a MODFLAGS variable for both
AS and CC. But in favour of consistency this was dropped.
So in some cases arch Makefile has one assignmnet replaced by
two assignmnets.

Note2: MODFLAGS was not documented and is dropped
without any notice. I do not expect much/any breakage
from this.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Acked-by: Mike Frysinger <vapier@gentoo.org> [blackfin]
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> [avr32]
Signed-off-by: Michal Marek <mmarek@suse.cz>

Documentation/kbuild/kbuild.txt

@@ -22,11 +22,23 @@ building C files and assembler files.
 
 KAFLAGS
 --------------------------------------------------
-Additional options to the assembler.
+Additional options to the assembler (for built-in and modules).
+
+AFLAGS_MODULE
+--------------------------------------------------
+Addtional module specific options to use for $(AS).
 
 KCFLAGS
 --------------------------------------------------
-Additional options to the C compiler.
+Additional options to the C compiler (for built-in and modules).
+
+CFLAGS_MODULE
+--------------------------------------------------
+Addtional module specific options to use for $(CC).
+
+LDFLAGS_MODULE
+--------------------------------------------------
+Additional options used for $(LD) when linking modules.
 
 KBUILD_VERBOSE
 --------------------------------------------------

Documentation/kbuild/makefiles.txt

@@ -928,11 +928,23 @@ When kbuild executes, the following steps are followed (roughly):
 	$(CFLAGS_KERNEL) contains extra C compiler flags used to compile
 	resident kernel code.
 
-    CFLAGS_MODULE	$(CC) options specific for modules
+    KBUILD_AFLAGS_MODULE   Options for $(AS) when building modules
 
-	$(CFLAGS_MODULE) contains extra C compiler flags used to compile code
-	for loadable kernel modules.
+	$(KBUILD_AFLAGS_MODULE) is used to add arch specific options that
+	are used for $(AS).
+	From commandline AFLAGS_MODULE shall be used (see kbuild.txt).
 
+    KBUILD_CFLAGS_MODULE   Options for $(CC) when building modules
+
+	$(KBUILD_CFLAGS_MODULE) is used to add arch specific options that
+	are used for $(CC).
+	From commandline CFLAGS_MODULE shall be used (see kbuild.txt).
+
+    KBUILD_LDFLAGS_MODULE   Options for $(LD) when linking modules
+
+	$(KBUILD_LDFLAGS_MODULE) is used to add arch specific options
+	used when linking modules. This is often a linker script.
+	From commandline LDFLAGS_MODULE shall be used (see kbuild.txt).
 
 --- 6.2 Add prerequisites to archprepare:
 

Makefile

@@ -332,10 +332,9 @@ CHECK		= sparse
 
 CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
 		  -Wbitwise -Wno-return-void $(CF)
-MODFLAGS	= -DMODULE
-CFLAGS_MODULE   = $(MODFLAGS)
-AFLAGS_MODULE   = $(MODFLAGS)
-LDFLAGS_MODULE  = -T $(srctree)/scripts/module-common.lds
+CFLAGS_MODULE   =
+AFLAGS_MODULE   =
+LDFLAGS_MODULE  =
 CFLAGS_KERNEL	=
 AFLAGS_KERNEL	=
 CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage
@@ -355,6 +354,9 @@ KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		   -Wno-format-security \
 		   -fno-delete-null-pointer-checks
 KBUILD_AFLAGS   := -D__ASSEMBLY__
+KBUILD_AFLAGS_MODULE  := -DMODULE
+KBUILD_CFLAGS_MODULE  := -DMODULE
+KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds
 
 # Read KERNELRELEASE from include/config/kernel.release (if it exists)
 KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
@@ -369,6 +371,7 @@ export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
 export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
 export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV
 export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
+export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
 
 # When compiling out-of-tree modules, put MODVERDIR in the module
 # tree rather than in the kernel tree. The kernel tree might
@@ -607,7 +610,7 @@ endif
 # Use --build-id when available.
 LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\
 			      $(call cc-ldoption, -Wl$(comma)--build-id,))
-LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
+KBUILD_LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
 LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)
 
 ifeq ($(CONFIG_STRIP_ASM_SYMS),y)

arch/avr32/Makefile

@@ -13,7 +13,7 @@ KBUILD_DEFCONFIG	:= atstk1002_defconfig
 
 KBUILD_CFLAGS	+= -pipe -fno-builtin -mno-pic
 KBUILD_AFLAGS	+= -mrelax -mno-pic
-CFLAGS_MODULE	+= -mno-relax
+KBUILD_CFLAGS_MODULE += -mno-relax
 LDFLAGS_vmlinux	+= --relax
 
 cpuflags-$(CONFIG_PLATFORM_AT32AP)	+= -march=ap

arch/blackfin/Makefile

@@ -15,8 +15,8 @@ GZFLAGS          := -9
 
 KBUILD_CFLAGS           += $(call cc-option,-mno-fdpic)
 KBUILD_AFLAGS           += $(call cc-option,-mno-fdpic)
-CFLAGS_MODULE    += -mlong-calls
-LDFLAGS_MODULE   += -m elf32bfin
+KBUILD_CFLAGS_MODULE    += -mlong-calls
+KBUILD_LDFLAGS_MODULE   += -m elf32bfin
 KALLSYMS         += --symbol-prefix=_
 
 KBUILD_DEFCONFIG := BF537-STAMP_defconfig

arch/ia64/Makefile

@@ -22,7 +22,7 @@ CHECKFLAGS	+= -m64 -D__ia64=1 -D__ia64__=1 -D_LP64 -D__LP64__
 
 OBJCOPYFLAGS	:= --strip-all
 LDFLAGS_vmlinux	:= -static
-LDFLAGS_MODULE	+= -T $(srctree)/arch/ia64/module.lds
+KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/ia64/module.lds
 AFLAGS_KERNEL	:= -mconstant-gp
 EXTRA		:=
 

arch/m32r/Makefile

@@ -13,7 +13,7 @@ LDFLAGS_vmlinux	:=
 
 KBUILD_CFLAGS += -pipe -fno-schedule-insns
 CFLAGS_KERNEL += -mmodel=medium
-CFLAGS_MODULE += -mmodel=large
+KBUILD_CFLAGS_MODULE += -mmodel=large
 
 ifdef CONFIG_CHIP_VDEC2
 cflags-$(CONFIG_ISA_M32R2)	+= -DNO_FPU -Wa,-bitinst

arch/m68k/Makefile

@@ -18,7 +18,7 @@ KBUILD_DEFCONFIG := multi_defconfig
 # override top level makefile
 AS += -m68020
 LDFLAGS := -m m68kelf
-LDFLAGS_MODULE += -T $(srctree)/arch/m68k/kernel/module.lds
+KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/m68k/kernel/module.lds
 ifneq ($(SUBARCH),$(ARCH))
 	ifeq ($(CROSS_COMPILE),)
 		CROSS_COMPILE := $(call cc-cross-prefix, \

arch/mips/Makefile

@@ -93,7 +93,8 @@ all-$(CONFIG_SYS_SUPPORTS_ZBOOT)+= vmlinuz
 cflags-y			+= -G 0 -mno-abicalls -fno-pic -pipe
 cflags-y			+= -msoft-float
 LDFLAGS_vmlinux			+= -G 0 -static -n -nostdlib
-MODFLAGS			+= -mlong-calls
+KBUILD_AFLAGS_MODULE		+= -mlong-calls
+KBUILD_CFLAGS_MODULE		+= -mlong-calls
 
 cflags-y += -ffreestanding
 
@@ -172,7 +173,8 @@ cflags-$(CONFIG_CPU_DADDI_WORKAROUNDS)	+= $(call cc-option,-mno-daddi,)
 
 ifdef CONFIG_CPU_SB1
 ifdef CONFIG_SB1_PASS_1_WORKAROUNDS
-MODFLAGS	+= -msb1-pass1-workarounds
+KBUILD_AFLAGS_MODULE += -msb1-pass1-workarounds
+KBUILD_CFLAGS_MODULE += -msb1-pass1-workarounds
 endif
 endif
 

arch/powerpc/Makefile

@@ -93,7 +93,7 @@ else
 	KBUILD_CFLAGS += $(call cc-option,-mtune=power4)
 endif
 else
-LDFLAGS_MODULE	+= arch/powerpc/lib/crtsavres.o
+KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o
 endif
 
 ifeq ($(CONFIG_TUNE_CELL),y)

arch/s390/Makefile

@@ -22,7 +22,8 @@ STACK_SIZE	:= 8192
 CHECKFLAGS	+= -D__s390__ -msize-long
 else
 LDFLAGS		:= -m elf64_s390
-MODFLAGS	+= -fpic -D__PIC__
+KBUILD_AFLAGS_MODULE += -fpic -D__PIC__
+KBUILD_CFLAGS_MODULE += -fpic -D__PIC__
 KBUILD_CFLAGS	+= -m64
 KBUILD_AFLAGS	+= -m64
 UTS_MACHINE	:= s390x

arch/score/Makefile

@@ -20,7 +20,8 @@ cflags-y += -G0 -pipe -mel -mnhwloop -D__SCOREEL__ \
 #
 KBUILD_AFLAGS += $(cflags-y)
 KBUILD_CFLAGS += $(cflags-y)
-MODFLAGS += -mlong-calls
+KBUILD_AFLAGS_MODULE += -mlong-calls
+KBUILD_CFLAGS_MODULE += -mlong-calls
 LDFLAGS += --oformat elf32-littlescore
 LDFLAGS_vmlinux	+= -G0 -static -nostdlib
 

scripts/Makefile.build

@@ -115,7 +115,10 @@ endif
 # ---------------------------------------------------------------------------
 
 # Default is built-in, unless we know otherwise
-modkern_cflags = $(if $(part-of-module), $(CFLAGS_MODULE), $(CFLAGS_KERNEL))
+modkern_cflags =                                          \
+	$(if $(part-of-module),                           \
+		$(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
+		$(CFLAGS_KERNEL))
 quiet_modtag := $(empty)   $(empty)
 
 $(real-objs-m)        : part-of-module := y
@@ -250,8 +253,8 @@ $(obj)/%.lst: $(src)/%.c FORCE
 
 modkern_aflags := $(AFLAGS_KERNEL)
 
-$(real-objs-m)      : modkern_aflags := $(AFLAGS_MODULE)
-$(real-objs-m:.o=.s): modkern_aflags := $(AFLAGS_MODULE)
+$(real-objs-m)      : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
+$(real-objs-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
 
 quiet_cmd_as_s_S = CPP $(quiet_modtag) $@
 cmd_as_s_S       = $(CPP) $(a_flags)   -o $@ $< 

scripts/Makefile.modpost

@@ -107,7 +107,7 @@ $(modules:.ko=.mod.c): __modpost ;
 modname = $(notdir $(@:.mod.o=))
 
 quiet_cmd_cc_o_c = CC      $@
-      cmd_cc_o_c = $(CC) $(c_flags) $(CFLAGS_MODULE)	\
+      cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
 		   -c -o $@ $<
 
 $(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
@@ -117,8 +117,9 @@ targets += $(modules:.ko=.mod.o)
 
 # Step 6), final link of the modules
 quiet_cmd_ld_ko_o = LD [M]  $@
-      cmd_ld_ko_o = $(LD) -r $(LDFLAGS) $(LDFLAGS_MODULE) -o $@		\
-			  $(filter-out FORCE,$^)
+      cmd_ld_ko_o = $(LD) -r $(LDFLAGS)                                 \
+                             $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
+                             -o $@ $(filter-out FORCE,$^)
 
 $(modules): %.ko :%.o %.mod.o FORCE
 	$(call if_changed,ld_ko_o)