Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures

Nicholas Piggin
2016-08-05T16:16:52Z

On Fri, 05 Aug 2016 18:01:13 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> On Friday, August 5, 2016 10:26:25 PM CEST Nicholas Piggin wrote:
> > On Fri, 05 Aug 2016 12:17:27 +0200
> > Arnd Bergmann <arnd@arndb.de> wrote:
>
> > > and I also get link errors for the .text.fixup section
> > > for any users of __put_user() in really large kernels:
> > > net/batman-adv/batman-adv.o:(.text.fixup+0x4): relocation truncated to fit: R_ARM_JUMP24 against `.text.batadv_log_read'
> >
> > This may be fixed by fixing the linker script to bring in the new
> > sections properly (see new patchset).
> >
> > If not, then if you can combine the sections rather than have them
> > consecutive in the output, e.g.,:
> >
> > *(.text .text.fixup)
> >
> > Rather than
> >
> > *(.text)
> > *(.text.fixup)
> >
> > Then the linker has more freedom to rearrange them. I realize it's
> > not that simple with ARM's .text.fixup, but maybe that helps you
> > get it to work.
>
> This did the trick:
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 0ec807d69f18..7a3ad269fa23 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -433,7 +433,7 @@
> * during second ld run in second ld pass when generating System.map */
> #define TEXT_TEXT \
> ALIGN_FUNCTION(); \
> - *(.text.hot .text .text.fixup .text.unlikely) \
> + *(.text.hot .text .text.* .text.fixup .text.unlikely) \
> *(.ref.text) \
> MEM_KEEP(init.text) \
> MEM_KEEP(exit.text) \
>
>
> It also got much faster again, the link time for an allyesconfig
> kernel is now 18 minutes instead of 10 hours, but it's still
> much worse than the 2 minutes I had earlier or the four minutes
> with the previous patch.

Are you using the patches I just sent? Either way, you also need
to do the same for data and bss sections as you are using
-fdata-sections too.

I've found virtually no build time regression on powerpc or x86
when those are taken care of properly (x86 numbers I sent are typo,
it's not 5m20, it's 5m02).

Thanks,
Nick