Hi, On Wed, Sep 7, 2011 at 3:07 PM, Nicolas Pitre <nico@xxxxxxxxxxx> wrote: > On Fri, 19 Aug 2011, Arnaud Lacombe wrote: > >> Hi folks, >> >> The attached patch modify Kbuild to allow to directly re-use code in multiple >> directory without having to go through a copy. Technically, it changes Kbuild to >> use by default the VPATH feature of GNU make and provides accessors for Makefile >> to change it indirectly. >> >> Considering: >> >> arch/foo/lib: >> fancy.c >> >> We want to be able to build it with -DPANTS=32 in the kernel, but the >> bootloader requires -DPANTS_SIZE=30. >> >> Currently we would do, either: >> >> arch/foo/lib/Makefile >> LDFLAGS_fancy.o := -DPANTS=32 >> obj-y += fancy.o >> >> and, either: >> >> arch/foo/boot/Makefile: >> LDFLAGS_fancy.o := -DPANTS=30 >> obj-y += fancy.o >> $(obj)/fancy.c: $(srctree)/arch/foo/lib/fancy.c >> $(call cmd,shipped) >> >> or >> >> arch/foo/boot/Makefile: >> LDFLAGS_fancy.o := -DPANTS=30 >> obj-y += fancy.o >> $(obj)/fancy.o: $(srctree)/arch/foo/lib/fancy.c >> $(call cmd,cc_c_o) >> >> The former implies an extra copy of the source file, the latter expose Kbuild >> internal function. >> >> With the attached patch, we would do: >> >> arch/foo/boot/Makefile: >> LDFLAGS_fancy.o := -DPANTS=30 >> obj-y += fancy.o >> vpath-y += $(srctree)/arch/foo/lib >> >> and let GNU make do the job. >> >> Comments welcome, > > It doesn't work. Whatever I do to arch/arm/boot/compressed/Makefile > (which admittedly looks a bit hairy and could benefit from a shave) in > order to remove the $(call cmd,shipped) used with lib1funcs.S, I always > end up with: > > make[2]: *** No rule to make target `arch/arm/boot/compressed/lib1funcs.S', needed by `arch/arm/boot/compressed/lib1funcs.o'. Stop. > What was the exact change you made which triggered this ? Thanks, - Arnaud > Obviously, restoring the explicit dependency with a $(call cmd,as_o_S) > does make it work, but this is rather against the point of your patch. > > Do you have an example of how arch/arm/boot/compressed/Makefile should > be changed to benefit from your patch? > > > Nicolas > -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
