Re: Build failure in -next due to 'kbuild: allow archs to select link dead code/data elimination'

[Guenter Roeck]

On 09/12/2016 08:51 PM, Nicholas Piggin wrote:
> On Mon, 12 Sep 2016 20:17:30 -0700
> Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> > Hi Nicholas,
> >
> > On 09/12/2016 07:00 PM, Nicholas Piggin wrote:
> > > On Mon, 12 Sep 2016 15:24:43 -0700
> > > Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> > >
> > > > Hi,
> > > >
> > > > your commit 'kbuild: allow archs to select link dead code/data elimination'
> > > > is causing the following build failure in -next when building score:defconfig.
> > > >
> > > > arch/score/kernel/built-in.o: In function `work_resched':
> > > > arch/score/kernel/entry.o:(.text+0xe84):
> > > > 	relocation truncated to fit: R_SCORE_PC19 against `schedule'
> > > >
> > > > Reverting the commit fixes the problem.
> > > >
> > > > Please let me know if I can help tracking down the problem.
> > > > In case you need a score toochain, you can find the one I use at
> > > > http://server.roeck-us.net/toolchains/score.tgz.
> > > >
> > > > Thanks,
> > > > Guenter
> > >
> > > It's not supposed to have any real effect unless the
> > > option is selected, but there are a few changes to linker
> > > script which must be causing it.
> > >
> > > There are two changes to vmlinux.lds.h. One is to KEEP a
> > > few input sections, that *should* be kept anyway. The other
> > > is to bring in additional sections into their correct output
> > > section.
> > >
> > > Could you try reverting those lines of vmlinux.lds.h that
> > > change the latter, i.e.:
> > >
> > > -		*(.text.hot .text .text.fixup .text.unlikely)		\
> > > +		*(.text.hot .text .text.fixup .text.unlikely .text.*)	\
> >
> > This is the culprit. After removing " .text.*" it builds fine.
>
> Thanks for testing it. Some architectures have .text.x sections
> not included here, I should have seen that. We should possibly
> just revert that line and require implementing archs to do the
> right thing.
I would call the build failure a regression, so it should either be
reverted, or we'll need some other solution to fix the build failure.

Thanks,
Guenter

> [ Convention is to use '.' to avoid C identifiers, so we should
> use .text..x for these things. But that's not done completely
> throughout the kernel, and a little invasive to do with this
> series. I'll revisit this and clean things up subsequently after
> this round gets merged. ]
>
> Thanks,
> Nick