Re: linux-next: build warnings from the build of Linus' tree

[Arnd Bergmann]

On Sat, Aug 25, 2018 at 8:53 PM Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
> On Fri, 24 Aug 2018 14:46:16 +0200
> Arnd Bergmann <arnd@xxxxxxxx> wrote:
> > On Fri, Aug 24, 2018 at 10:23 AM Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
> > >
> > > On Fri, 24 Aug 2018 13:32:06 +1000
> > > Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
> > >
> > > > Hi all,
> > > >
> > > > After merging the origin tree, today's linux-next build (powerpc
> > > > allyesconfig) produced these warnings:
> > > >
> > > > Maybe introduced by commit
> > > >
> > > >   6b7dca401cb1 ("tracing: Allow gcov profiling on only ftrace subsystem")
> > > >
> > > > I am guessing, but that is the only new thing that affects all of
> > > > kernel/trace ...
> > >
> > > Yes, I agree. But I just followed Documentation/dev-tools/gcov.rst
> > > to enable profiling in kernel/trace. Hmm, doesn't ppc64 support
> > > GCOV_PROFILE?  (But as far as I can see, ARCH_HAS_GCOV_PROFILE_ALL
> > > is enabled in arch/powerpc/Kconfig)
> > >
> > > Anyway, I'll try to reproduce it.
> >
> > Thje same commit causes a link failure on ARM with a randconfig
> > kernel (see https://pastebin.com/KspjpyKG for the .config):
>
> OK, I confirmed that this happened with both gcc-7.3.0 and gcc-8.1.0
> with your config.
> I also confirmed that CONFIG_GCOV_PROFILE_ALL causes same issue.
> (Note that CONFIG_GCOV_PROFILE_ALL depends on !CONFIG_COMPILE_TEST,
>  so allyesconfig disables it always)
>
> Hmm, now gcov kernel itself might have a problem on arm and
> powerpc(on gcc-8)?

Yes, that is very possible. I always force CONFIG_COMPILE_TEST=y
in my randconfig tests, so I miss that kind of problem.

      Arnd