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: Sam Ravnborg <sam@ravnborg.org>
diff --git a/Documentation/kbuild/modules.txt b/Documentation/kbuild/modules.txt
index 7e77f93..87d858d 100644
--- a/Documentation/kbuild/modules.txt
+++ b/Documentation/kbuild/modules.txt
@@ -13,6 +13,7 @@
--- 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 @@
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
diff --git a/Makefile b/Makefile
index 77a448c..639d8a4 100644
--- a/Makefile
+++ b/Makefile
@@ -137,7 +137,7 @@
src := $(srctree)
obj := $(objtree)
-VPATH := $(srctree)
+VPATH := $(srctree):$(KBUILD_EXTMOD)
export srctree objtree VPATH TOPDIR
@@ -849,27 +849,6 @@
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 @@
@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 @@
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
# ===========================================================================