From: Arnd Bergmann <arnd@arndb.de>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] compiler-gcc: require gcc 4.8 for powerpc __builtin_bswap16()
Date: Mon, 09 May 2016 12:16:11 +0200 [thread overview]
Message-ID: <75773040.xkfFJb3GoQ@wuerfel> (raw)
In-Reply-To: <1462786493.5531.1.camel@ellerman.id.au>
On Monday 09 May 2016 19:34:53 Michael Ellerman wrote:
> On Mon, 2016-05-09 at 16:33 +1000, Stephen Rothwell wrote:
> > On Mon, 9 May 2016 10:59:27 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> > > On Fri, 6 May 2016 09:22:25 -0500 Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > > > diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
> > > > index eeae401..3d5202e 100644
> > > > --- a/include/linux/compiler-gcc.h
> > > > +++ b/include/linux/compiler-gcc.h
> > > > @@ -246,7 +246,7 @@
> > > > #define __HAVE_BUILTIN_BSWAP32__
> > > > #define __HAVE_BUILTIN_BSWAP64__
> > > > #endif
> > > > -#if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600)
> > > > +#if GCC_VERSION >= 40800
> > > > #define __HAVE_BUILTIN_BSWAP16__
> > > > #endif
> > > > #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
> >
> > Tested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
> > Michael, do you want to pass the fix patch on, or will I submit it
> > directly to Linus?
>
> I'm happy for you to send it, I haven't actually hit the bug myself.
I found the commit in gcc-4.8 that replaced the powerpc-specific implementation
of __builtin_bswap16 with an architecture-independent one. Apparently the
powerpc version (gcc-4.6 and 4.7) just mapped to the lhbrx/sthbrx instructions,
so it ended up not being a constant, though the intent of the patch was
mainly to add support for the builtin to x86.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52624 has the patch that went
into gcc-4.8 and more information.
Arnd
next prev parent reply other threads:[~2016-05-09 10:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-06 4:58 linux-next: build failure after merge of the akpm-current tree Stephen Rothwell
2016-05-06 5:44 ` Andrew Morton
2016-05-06 6:09 ` Stephen Rothwell
2016-05-06 6:55 ` Michael Ellerman
2016-05-06 14:22 ` [PATCH] compiler-gcc: require gcc 4.8 for powerpc __builtin_bswap16() Josh Poimboeuf
2016-05-09 0:59 ` Stephen Rothwell
2016-05-09 5:39 ` Sedat Dilek
2016-05-09 8:31 ` Stephen Rothwell
2016-05-09 6:33 ` Stephen Rothwell
2016-05-09 9:34 ` Michael Ellerman
2016-05-09 10:16 ` Arnd Bergmann [this message]
2016-05-09 10:36 ` Stephen Rothwell
2016-06-15 9:33 ` linux-next: build failure after merge of the akpm-current tree Paul Bolle
2016-06-15 14:03 ` Josh Poimboeuf
2016-06-15 21:12 ` Paul Bolle
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