MIPS parallel build breakage

[Sascha Hauer]

On Fri, Mar 02, 2018 at 03:17:35PM +0300, Antony Pavlov wrote:
> On Thu, 1 Mar 2018 12:07:29 +0100
> Sascha Hauer <s.hauer at pengutronix.de> wrote:
> 
> > Hi Sam and Antony,
> > 
> > (Antony because you introduced this and Sam because you have intimate
> > knowledge with our build system ;)
> > 
> > I am trying to solve a problem that annoys me for some years now. The
> > problem is that the MIPS defconfigs regularly fail in my autobuilder.
> > I usually help myself with trying it again and most of the time it
> > then works, but doing this for years increases the pressure to do
> > something.
> > 
> > What happens is that the MIPS builds use include/generated/compile.h:
> > 
> > > arch/mips/include/asm/pbl_macros.h:28:#include <generated/compile.h>
> > 
> > This often ends in:
> > 
> > > In file included from arch/mips/boot/start.S:20:0: arch/mips/include/asm/pbl_macros.h:28:31:
> > > fatal error: generated/compile.h: No such file or directory
> > > compilation terminated.
> > 
> > include/generated/compile.h is generated in common/Makefile:
> > 
> > > include/generated/compile.h: FORCE
> > > 	@$($(quiet)chk_compile.h)
> > > 	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkcompile_h $@ \
> > > 	"$(UTS_MACHINE)" "$(CC) $(KBUILD_CFLAGS)"
> > 
> > Other users of this file add an explicit dependency on it:
> > 
> > > # dependencies on generated files need to be listed explicitly
> > > $(obj)/version.o: include/generated/compile.h
> > 
> > This only seems to work though when the dependent file is in the same
> > directory, but not when the file is in arch/mips/boot/.
> > 
> > I tried doing the include/generated/compile.h in Makefile instead of
> > common/Makefile, but then the version counting gets confused and causes
> > unnecessary rebuilds.
> > 
> > Any ideas how to solve this?
> 
> I can't reproduce parallel build breakage.

The failure starts here when using 6 threads or more and only when
compiling the black-swift_defconfig. After one successful build I can
reproduce this reliably here with:

rm -f include/generated/compile.h && make -j 6

> But I see another problem:
> the version string inside mips pbl binary is differ from the version string
> inside main barebox binary.
> 
> I suppose that the problem is that current build system handles mips asm files
> (which are actually use generated compile.h) and c-files in a different way.

Ups. How do the strings differ?

Another obvious way to fix the issue is to remove UTS_RELEASE and
UTS_VERSION from the pbl headers. Would that be an option?

Sascha


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