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| author | Masahiro Yamada <masahiroy@kernel.org> | 2024-11-10 10:34:35 +0900 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2024-11-28 08:11:55 +0900 |
| commit | 11b3d5175e6bc3779159228e6077be202d2b0069 (patch) | |
| tree | 8b85efcc9a4538c3e23c0beb7145f6a55f90f96d /Makefile | |
| parent | bad6beb2c0bb982b830f592a7b3e3eee76cbb85a (diff) | |
| download | lwn-11b3d5175e6bc3779159228e6077be202d2b0069.tar.gz lwn-11b3d5175e6bc3779159228e6077be202d2b0069.zip | |
kbuild: support building external modules in a separate build directory
There has been a long-standing request to support building external
modules in a separate build directory.
This commit introduces a new environment variable, KBUILD_EXTMOD_OUTPUT,
and its shorthand Make variable, MO.
A simple usage:
$ make -C <kernel-dir> M=<module-src-dir> MO=<module-build-dir>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Diffstat (limited to 'Makefile')
| -rw-r--r-- | Makefile | 20 |
1 files changed, 18 insertions, 2 deletions
@@ -134,6 +134,10 @@ ifeq ("$(origin M)", "command line") KBUILD_EXTMOD := $(M) endif +ifeq ("$(origin MO)", "command line") + KBUILD_EXTMOD_OUTPUT := $(MO) +endif + $(if $(word 2, $(KBUILD_EXTMOD)), \ $(error building multiple external modules is not supported)) @@ -187,7 +191,7 @@ ifdef KBUILD_EXTMOD else objtree := $(CURDIR) endif - output := $(KBUILD_EXTMOD) + output := $(or $(KBUILD_EXTMOD_OUTPUT),$(KBUILD_EXTMOD)) # KBUILD_EXTMOD might be a relative path. Remember its absolute path before # Make changes the working directory. srcroot := $(realpath $(KBUILD_EXTMOD)) @@ -645,6 +649,7 @@ quiet_cmd_makefile = GEN Makefile } > Makefile outputmakefile: +ifeq ($(KBUILD_EXTMOD),) @if [ -f $(srctree)/.config -o \ -d $(srctree)/include/config -o \ -d $(srctree)/arch/$(SRCARCH)/include/generated ]; then \ @@ -654,7 +659,16 @@ outputmakefile: echo >&2 "***"; \ false; \ fi - $(Q)ln -fsn $(srctree) source +else + @if [ -f $(srcroot)/modules.order ]; then \ + echo >&2 "***"; \ + echo >&2 "*** The external module source tree is not clean."; \ + echo >&2 "*** Please run 'make -C $(abs_srctree) M=$(realpath $(srcroot)) clean'"; \ + echo >&2 "***"; \ + false; \ + fi +endif + $(Q)ln -fsn $(srcroot) source $(call cmd,makefile) $(Q)test -e .gitignore || \ { echo "# this is build directory, ignore it"; echo "*"; } > .gitignore @@ -1940,6 +1954,8 @@ KBUILD_MODULES := 1 endif +prepare: outputmakefile + # Preset locale variables to speed up the build process. Limit locale # tweaks to this spot to avoid wrong language settings when running # make menuconfig etc. |