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Commit 06300b21 authored by Sam Ravnborg's avatar Sam Ravnborg
Browse files

kbuild: support building individual files for external modules 



Support building individual files when dealing with separate modules.
So say you have a module named "foo" which consist of two .o files bar.o
and fun.o.

You can then do:
make -C $KERNELSRC M=`pwd` bar.o
make -C $KERNELSRC M=`pwd` bar.lst
make -C $KERNELSRC M=`pwd` bar.i
make -C $KERNELSRC M=`pwd` /            <= will build all .o files
                                           and link foo.o
make -C $KERNELSRC M=`pwd` foo.ko       <= will build the module
                                           and do the modpost step
					   to create foo.ko

The above will also work if the external module is placed in a
subdirectory using a hirachy of kbuild files.
Thanks to Andreas Gruenbacher <agruen@suse.de> for initial feature
request / bug report.

Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
parent bd71c2b1

Documentation/kbuild/modules.txt

+11 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ In this document you will find information about: 
	   --- 2.2 Available targets

	   --- 2.3 Available options

	   --- 2.4 Preparing the kernel tree for module build

	   --- 2.5 Building separate files for a module

	=== 3. Example commands

	=== 4. Creating a kbuild file for an external module

	=== 5. Include files
@@ -131,6 +132,16 @@ when building an external module. 
	      Therefore a full kernel build needs to be executed to make

	      module versioning work.



--- 2.5 Building separate files for a module

	It is possible to build single files which is part of a module.

	This works equal for the kernel, a module and even for external

	modules.

	Examples (module foo.ko, consist of bar.o, baz.o):

		make -C $KDIR M=`pwd` bar.lst

		make -C $KDIR M=`pwd` bar.o

		make -C $KDIR M=`pwd` foo.ko

		make -C $KDIR M=`pwd` /

	



=== 3. Example commands

Makefile

+44 −22
Original line number Diff line number Diff line
@@ -137,7 +137,7 @@ objtree := $(CURDIR) 
src		:= $(srctree)

obj		:= $(objtree)



VPATH		:= $(srctree)

VPATH		:= $(srctree):$(KBUILD_EXTMOD)



export srctree objtree VPATH TOPDIR
@@ -849,27 +849,6 @@ prepare prepare-all: prepare0 


export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH)



# Single targets

# ---------------------------------------------------------------------------



%.s: %.c scripts FORCE

	$(Q)$(MAKE) $(build)=$(@D) $@

%.i: %.c scripts FORCE

	$(Q)$(MAKE) $(build)=$(@D) $@

%.o: %.c scripts FORCE

	$(Q)$(MAKE) $(build)=$(@D) $@

%.ko: scripts FORCE

	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) $(build)=$(@D) $(@:.ko=.o)

	$(Q)$(MAKE) -rR -f $(srctree)/scripts/Makefile.modpost

%/:      scripts prepare FORCE

	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) $(build)=$(@D)

%.lst: %.c scripts FORCE

	$(Q)$(MAKE) $(build)=$(@D) $@

%.s: %.S scripts FORCE

	$(Q)$(MAKE) $(build)=$(@D) $@

%.o: %.S scripts FORCE

	$(Q)$(MAKE) $(build)=$(@D) $@



# 	FIXME: The asm symlink changes when $(ARCH) changes. That's

#	hard to detect, but I suppose "make mrproper" is a good idea

#	before switching between archs anyway.
@@ -1192,6 +1171,11 @@ help: 
	@echo  '  modules_install - install the module'

	@echo  '  clean           - remove generated files in module directory only'

	@echo  ''



# Dummies...

.PHONY: prepare scripts

prepare: ;

scripts: ;

endif # KBUILD_EXTMOD



# Generate tags for editors
@@ -1313,6 +1297,44 @@ kernelrelease: 
kernelversion:

	@echo $(KERNELVERSION)



# Single targets

# ---------------------------------------------------------------------------

# The directory part is taken from first prerequisite, so this

# works even with external modules

%.s: %.c scripts FORCE

	$(Q)$(MAKE) $(build)=$(dir $<) $(dir $<)$(notdir $@)

%.i: %.c scripts FORCE

	$(Q)$(MAKE) $(build)=$(dir $<) $(dir $<)$(notdir $@)

%.o: %.c scripts FORCE

	$(Q)$(MAKE) $(build)=$(dir $<) $(dir $<)$(notdir $@)

%.lst: %.c scripts FORCE

	$(Q)$(MAKE) $(build)=$(dir $<) $(dir $<)$(notdir $@)

%.s: %.S scripts FORCE

	$(Q)$(MAKE) $(build)=$(dir $<) $(dir $<)$(notdir $@)

%.o: %.S scripts FORCE

	$(Q)$(MAKE) $(build)=$(dir $<) $(dir $<)$(notdir $@)



# For external modules we shall include any directory of the target,

# but usual case there is no directory part.

# make M=`pwd` module.o     => $(dir $@)=./

# make M=`pwd` foo/module.o => $(dir $@)=foo/

# make M=`pwd` /            => $(dir $@)=/

 

ifeq ($(KBUILD_EXTMOD),)

        target-dir = $(@D)

else

        zap-slash=$(filter-out .,$(patsubst %/,%,$(dir $@)))

        target-dir = $(KBUILD_EXTMOD)$(if $(zap-slash),/$(zap-slash))

endif



/ %/:      scripts prepare FORCE

	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \

	$(build)=$(target-dir)

%.ko: scripts FORCE

	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \

	$(build)=$(target-dir) $(@:.ko=.o)

	$(Q)$(MAKE) -rR -f $(srctree)/scripts/Makefile.modpost



# FIXME Should go into a make.lib or something 

# ===========================================================================