On Thu, Dec 21, 2017 at 05:53:02PM -0800, Douglas Anderson wrote:
> Several people reported that the commit 3298b690b21c ("kbuild: Add a
> cache for generated variables") caused them problems when they updated
> gcc versions. Specifically the reports all looked something similar
> to this:
>
> > In file included from ./include/uapi/linux/uuid.h:21:0,
> > from ./include/linux/uuid.h:19,
> > from ./include/linux/mod_devicetable.h:12,
> > from scripts/mod/devicetable-offsets.c:2:
> > ./include/linux/string.h:8:20: fatal error: stdarg.h: No such file or
> > directory
> > #include <stdarg.h>
>
> Masahiro Yamada determined that the problem was with:
>
> NOSTDINC_FLAGS += -nostdinc -isystem $(call shell-cached,$(CC)
> -print-file-name=include)
>
> Specifically that the stale result of -print-file-name is stored in
> the cache file. It was determined that a "make clean" fixed the
> problems in all cases.
>
> In this particular case we could certainly try to clean just the cache
> when we detect a gcc update, but it seems like overall it's a bad idea
> to do an incremental build when gcc changes. We should warn the user
> and tell them that they need a 'make clean'.
>
> Fixes: 3298b690b21c ("kbuild: Add a cache for generated variables")
> Reported-by: Yang Shi <[email protected]>
> Reported-by: Dave Hansen <[email protected]>
> Reported-by: Mathieu Malaterre <[email protected]>
> Signed-off-by: Douglas Anderson <[email protected]>
Unfortunately, it doesn't work as-is. Trying to build for mips with two
different compilers, and trying to run "make clean" with the 2nd compiler
version, results in:
scripts/Kbuild.include:490: *** Detected new CC version (050400 vs 040803).
Please 'make clean'. Stop.
Makefile:1297: recipe for target '_clean_.' failed
make: *** [_clean_.] Error 2
make: *** Waiting for unfinished jobs....
scripts/Kbuild.include:490: *** Detected new CC version (050400 vs 040803).
Please 'make clean'. Stop.
Makefile:1297: recipe for target '_clean_arch/mips' failed
make: *** [_clean_arch/mips] Error 2
scripts/Kbuild.include:490: *** Detected new CC version (050400 vs 040803).
Please 'make clean'. Stop.
Makefile:1297: recipe for target '_clean_arch/mips/boot/dts' failed
make: *** [_clean_arch/mips/boot/dts] Error 2
make: *** wait: No child processes. Stop.
Guenter
