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Re: RELEASE BLOCKER: Linux doesn't follow x86/x86-64 ABI wrt direction flag
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: "H. Peter Anvin" <hpa at zytor dot com>
- Cc: "Jakub Jelinek" <jakub at redhat dot com>, NightStrike <nightstrike at gmail dot com>, "Olivier Galibert" <galibert at pobox dot com>, "Chris Lattner" <clattner at apple dot com>, "Michael Matz" <matz at suse dot de>, "Richard Guenther" <richard dot guenther at gmail dot com>, "Joe Buck" <Joe dot Buck at synopsys dot com>, "Jan Hubicka" <hubicka at ucw dot cz>, "Aurelien Jarno" <aurelien at aurel32 dot net>, linux-kernel at vger dot kernel dot org, gcc at gcc dot gnu dot org
- Date: Thu, 6 Mar 2008 09:14:00 -0800
- Subject: Re: RELEASE BLOCKER: Linux doesn't follow x86/x86-64 ABI wrt direction flag
- References: <738B72DB-A1D6-43F8-813A-E49688D05771@apple.com> <578FCA7D-D7A6-44F6-9310-4A97C13CDCBE@apple.com> <47CF44E7.3020106@zytor.com> <20080306135139.GA5236@dspnet.fr.eu.org> <b609cb3b0803060737xa0c3c0byb51d51af797eb81f@mail.gmail.com> <6dc9ffc80803060743h502fc96bj6117ef87a8555c3a@mail.gmail.com> <47D012B4.3020104@zytor.com> <20080306162353.GF24887@devserv.devel.redhat.com> <6dc9ffc80803060858i7d4e8b56o99ff8ad301a5cc1a@mail.gmail.com> <47D024AA.9010300@zytor.com>
On Thu, Mar 6, 2008 at 9:06 AM, H. Peter Anvin <hpa@zytor.com> wrote:
>
> H.J. Lu wrote:
> > On Thu, Mar 6, 2008 at 8:23 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> >> On Thu, Mar 06, 2008 at 07:50:12AM -0800, H. Peter Anvin wrote:
> >> > H.J. Lu wrote:
> >> > >I agree with it. There is no right or wrong here Let's start from
> >> > >scratch and figure out
> >> > >what is the best way to handle this, assuming we are defining a new psABI.
> >>
> >> BTW, just tested icc and icc doesn't generate cld either (so it matches the
> >> new gcc behavior).
> >> char buf1[32], buf2[32];
> >> void bar (void);
> >> void foo (void)
> >> {
> >> __builtin_memset (buf1, 0, 32);
> >> bar ();
> >> __builtin_memset (buf2, 0, 32);
> >> }
> >>
> >
> > Icc follows the psABI. If we are saying icc/gcc 4.3 need a fix, we'd
> > better define
> > a new psABI first.
> >
>
> Not a fix, an (optional) workaround for a system bug.
>
So that is the bug in the Linux kernel. Since fixing kernel is much easier
than providing a workaround in compilers, I think kernel should be fixed
and no need for icc/gcc fix.
H.J.