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SubjectRe: [PATCH] kbuild: reuse vmlinux.o in vmlinux_link
+ Michael, and PPC ML.

They may know something about the reason of failure.


On Sat, May 23, 2020 at 2:41 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Fri, May 22, 2020 at 5:27 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> >
> > Instead of linking all compilation units again each time vmlinux_link is
> > called, reuse vmlinux.o from modpost_link.
> >
> > With x86_64 allyesconfig, vmlinux_link is called three times and reusing
> > vmlinux.o reduces the build time ~38 seconds on my system (59% reduction
> > in the time spent in vmlinux_link).
> >
> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > ---
> > scripts/link-vmlinux.sh | 5 +----
> > 1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> > index d09ab4afbda4..c6cc4305950c 100755
> > --- a/scripts/link-vmlinux.sh
> > +++ b/scripts/link-vmlinux.sh
> > @@ -77,11 +77,8 @@ vmlinux_link()
> >
> > if [ "${SRCARCH}" != "um" ]; then
> > objects="--whole-archive \
> > - ${KBUILD_VMLINUX_OBJS} \
> > + vmlinux.o \
> > --no-whole-archive \
> > - --start-group \
> > - ${KBUILD_VMLINUX_LIBS} \
> > - --end-group \
> > ${@}"
> >
> > ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
> >
> > base-commit: b85051e755b0e9d6dd8f17ef1da083851b83287d
> > --
> > 2.27.0.rc0.183.gde8f92d652-goog
> >
>
>
> I like this patch irrespective of CLANG_LTO, but
> unfortunately, my build test failed.
>
>
> ARCH=powerpc failed to build as follows:
>
>
>
> MODPOST vmlinux.o
> MODINFO modules.builtin.modinfo
> GEN modules.builtin
> LD .tmp_vmlinux.kallsyms1
> vmlinux.o:(__ftr_alt_97+0x20): relocation truncated to fit:
> R_PPC64_REL14 against `.text'+4b1c
> vmlinux.o:(__ftr_alt_97+0x164): relocation truncated to fit:
> R_PPC64_REL14 against `.text'+1cf78
> vmlinux.o:(__ftr_alt_97+0x288): relocation truncated to fit:
> R_PPC64_REL14 against `.text'+1dac4
> vmlinux.o:(__ftr_alt_97+0x2f0): relocation truncated to fit:
> R_PPC64_REL14 against `.text'+1e254
> make: *** [Makefile:1125: vmlinux] Error 1
>
>
>
> I used powerpc-linux-gcc
> available at
> https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/9.2.0/
>
>
> Build command:
>
> make -j24 ARCH=powerpc CROSS_COMPILE=powerpc-linux- defconfig all
>
>
> Could you check it please?
>
>
>
> I will apply it to my test branch.
> Perhaps, 0-day bot may find more failure cases.
>
>
> --
> Best Regards
> Masahiro Yamada



--
Best Regards
Masahiro Yamada

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