MIPS parallel build breakage

[Michael Olbrich]

Hi,

On Thu, Mar 01, 2018 at 12:07:29PM +0100, Sascha Hauer wrote:
> (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?

arch/mips/boot/: common/

in arch/mips/Makefile or something like that? These two are both targets of the
toplevel make call, so that should work. The same for $(BOARD), I think and
maybe others that include generated/compile.h.

Michael

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