Re: Debian x86 32-bits built for i586 !?
On Sun, 15 May 2011, Mike Hommey wrote:
> I just found out that gcc is compiled with --with-arch-32=i586, which
> effectively means it builds with -march=i586 by default (and that it
> still claims an i486-linux-gnu target).
> I'm wondering. Is the project at large aware that we're not building for
> i486, but for i586 ? That even the maintainer doesn't know why for
No. And unless we got a bug report form an i486 user, our users
probably didn't notice it either.
What are the *exact* differences between code generated for march=i486
to code generated for march=i586? What CPUs would break?
> > >I believe, that even plain i486 have to be supported,
> > >also changelog claims that default should still be i486.
> > yes, I think I did change that to avoid libgomp failures, which
> > requires i586, and not just i486. Not sure what to do about that
> > for squeeze.
> > $ apt-cache rdepends libgomp1 | wc -l
> > 77
> > So all these packages would need setting of the -march flag explicitly.
> > There are other packages which do require i586, like OpenJDK.
We may well consider switching the i386 port to i586. But lets access
the real impact, first. And whether we still have enough *active* i486
users (or i586-like CPUs that do not support gcc march=i586 if such a
thing could happen) to care.
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot