Re: Build/boot problem with 7b4537199a4a (Re: [PATCH v6 02/10] kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS)

[Masahiro Yamada]

On Sat, Aug 20, 2022 at 7:02 PM Christophe Leroy
<christophe.leroy@xxxxxxxxxx> wrote:
>
> Hi,
>
> Le 13/05/2022 à 13:39, Masahiro Yamada a écrit :
> > include/{linux,asm-generic}/export.h defines a weak symbol, __crc_*
> > as a placeholder.
> >
> > Genksyms writes the version CRCs into the linker script, which will be
> > used for filling the __crc_* symbols. The linker script format depends
> > on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset
> > to the reference of CRC.
> >
> > It is time to get rid of this complexity.
> >
> > Now that modpost parses text files (.*.cmd) to collect all the CRCs,
> > it can generate C code that will be linked to the vmlinux or modules.
> >
> > Generate a new C file, .vmlinux.export.c, which contains the CRCs of
> > symbols exported by vmlinux. It is compiled and linked to vmlinux in
> > scripts/link-vmlinux.sh.
> >
> > Put the CRCs of symbols exported by modules into the existing *.mod.c
> > files. No additional build step is needed for modules. As before,
> > *.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal.
> >
> > No linker magic is used here. The new C implementation works in the
> > same way, whether CONFIG_RELOCATABLE is enabled or not.
> > CONFIG_MODULE_REL_CRCS is no longer needed.
> >
> > Previously, Kbuild invoked additional $(LD) to update the CRCs in
> > objects, but this step is unneeded too.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> > Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> > Tested-by: Nicolas Schier <nicolas@xxxxxxxxx>
> > Reviewed-by: Nicolas Schier <nicolas@xxxxxxxxx>
>
> Problem with v6.0-rc1
> Problem with v5.19
> No problem with v5.18
>
> Bisected to 7b4537199a4a ("kbuild: link symbol CRCs at final link,
> removing CONFIG_MODULE_REL_CRCS")
>
> The above patch leads to the following problem building
> mpc85xx_defconfig + CONFIG_RELOCATABLE



Is this because the relocation implementation on ppc is incomplete?
(and is it the reason why relock_check.sh exists?)

arch/powerpc/kernel/reloc_32.S does not support R_PPC_UADDR32


-- 
Best Regards
Masahiro Yamada