On Thu, Jul 07, 2016 at 12:23:25PM +0100, Catalin Marinas wrote: > On Thu, Jul 07, 2016 at 11:26:01AM +0100, Catalin Marinas wrote: > > On Wed, Jul 06, 2016 at 06:57:39PM +0100, Catalin Marinas wrote: > > > On Thu, May 12, 2016 at 05:39:15PM +0100, Kevin Brodsky wrote: > > > > +# We need to generate vdso-offsets.h before compiling certain files in kernel/. > > > > +# In order to do that, we should use the archprepare target, but we can't since > > > > +# asm-offsets.h is included in some files used to generate vdso-offsets.h, and > > > > +# asm-offsets.h is built in prepare0, for which archprepare is a dependency. > > > > +# Therefore we need to generate the header after prepare0 has been made, hence > > > > +# this hack. > > > > +prepare: vdso_prepare > > > > +vdso_prepare: prepare0 > > > > + $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso include/generated/vdso-offsets.h > > > > > > This indeed looks dodgy. I'm not sure about the makefile rules but would > > > the above override the "prepare" target in the top Makefile? > > > > > > I think a dependency problem we have is that arch/arm64/kernel/signal.o > > > depends on include/generated/vdso-offsets.h. However, we don't have any > > > target for the latter, only for > > > $(objtree)arch/arm64/kernel/vdso/vdso-offsets.h which no-one is > > > including. Because of this, we have a fake dependency in > > > arch/arm64/kernel/Makefile. > > > > > > -----------8<------------------------- > > > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile > > > index 7700c0c23962..9bdacbf59091 100644 > > > --- a/arch/arm64/kernel/Makefile > > > +++ b/arch/arm64/kernel/Makefile > > > @@ -55,5 +55,4 @@ head-y := head.o > > > extra-y += $(head-y) vmlinux.lds > > > > > > # vDSO - this must be built first to generate the symbol offsets > > > -$(call objectify,$(arm64-obj-y)): $(obj)/vdso/vdso-offsets.h > > > -$(obj)/vdso/vdso-offsets.h: $(obj)/vdso > > > +$(objtree)/include/generated/vdso-offsets.h: $(obj)/vdso > > > > This didn't work either. Basically, when building > > arch/arm64/kernel/signal.o for example, it doesn't figure out that > > vdso-offsets.h has additional dependencies like the vdso.so.dbg so that > > it builds the vdso object first. I'll look for a little longer, maybe I > > find a better workaround. > > If I also add the patch below, it works fine but I'm not sure we can > guarantee that kbuild first dives into subdirectories with a parallel > build: > > --- a/arch/arm64/kernel/Makefile > +++ b/arch/arm64/kernel/Makefile > @@ -49,11 +49,7 @@ arm64-obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.o > arm64-obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o \ > cpu-reset.o > > -obj-y += $(arm64-obj-y) vdso/ > +obj-y += vdso/ $(arm64-obj-y) This one works "most of the time" but not always. What I found to work reliably (until further notice ;)) is to force the vdso build like below: ----------------------8<---------------------------- diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 7700c0c23962..366e4f26071f 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -55,5 +55,5 @@ head-y := head.o extra-y += $(head-y) vmlinux.lds # vDSO - this must be built first to generate the symbol offsets -$(call objectify,$(arm64-obj-y)): $(obj)/vdso/vdso-offsets.h -$(obj)/vdso/vdso-offsets.h: $(obj)/vdso +$(objtree)/include/generated/vdso-offsets.h: $(obj)/vdso + $(Q)$(MAKE) $(build)=$< $@ diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index b467fd0a384b..238bb2db76be 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -23,7 +23,7 @@ GCOV_PROFILE := n ccflags-y += -Wl,-shared obj-y += vdso.o -extra-y += vdso.lds vdso-offsets.h +extra-y += vdso.lds ../../../../include/generated/vdso-offsets.h CPPFLAGS_vdso.lds += -P -C -U$(ARCH) # Force dependency (incbin is bad) @@ -42,11 +42,10 @@ $(obj)/%.so: $(obj)/%.so.dbg FORCE gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh quiet_cmd_vdsosym = VDSOSYM $@ define cmd_vdsosym - $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@ && \ - cp $@ include/generated/ + $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@ endef -$(obj)/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE +$(objtree)/include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE $(call if_changed,vdsosym) # Assembly rules for the .S files ----------------------8<---------------------------- This was my last attempt at solving this. Unless someone has a better idea or thinkg the above doesn't work (or it's uglier than Kevin's original patch) I plan to merge it. Other advantages are that it only generates a single vdso-offets.h file. It also only rebuilds those objects that depend on vdso-offests.h rather than everything under arch/arm64/kernel/ (Kevin's patch was also solving this). -- Catalin -- 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
