On Wed, 7 Sep 2011, Arnaud Lacombe wrote: > 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 $(call cmd,shipped) used with lib1funcs.S, I always > > end up with: > > > > make[2]: *** No rule to make target `arch/arm/boot/compressed/lib1funcs.S', needed by `arch/arm/boot/compressed/lib1funcs.o'. Stop. > > > What was the exact change you made which triggered this ? In its simplest expression (not caring about the now undefined lib1funcs variable): diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile index 0c74a6fab9..b34ed80977 100644 --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile @@ -70,6 +70,10 @@ ifeq ($(CONFIG_ARCH_SHMOBILE),y) OBJS += head-shmobile.o endif +# For __aeabi_uidivmod +OBJS += lib1funcs.o +vpath-y += $(srctree)/arch/arm/lib + # # We now have a PIC decompressor implementation. Decompressors running # from RAM should not define ZTEXTADDR. Decompressors running directly @@ -120,12 +124,6 @@ LDFLAGS_vmlinux += -X # Next argument is a linker script LDFLAGS_vmlinux += -T -# For __aeabi_uidivmod -lib1funcs = $(obj)/lib1funcs.o - -$(obj)/lib1funcs.S: $(srctree)/arch/$(SRCARCH)/lib/lib1funcs.S FORCE - $(call cmd,shipped) - # We need to prevent any GOTOFF relocs being used with references # to symbols in the .bss section since we cannot relocate them # independently from the rest at run time. This can be achieved by Nicolas
