Jakub's Recommendations for ia32 Support

Adam Jackson ajax at redhat.com
Wed Feb 4 16:06:04 UTC 2009


On Wed, 2009-02-04 at 16:01 +0100, Peter Robinson wrote:
> >> >> So we should ignore OLPC that is deploying 100's of thousands all
> >> >> running Fedora?
> >> >
> >> > Modest proposal: OLPC might benefit from running its own koji instance
> >> > and effectively going the secondary arch route.  -Os -march=geode, etc.
> >> > Given how close it is to mainline x86 it's unlikely to have funky
> >> > compilation failures, and it has to branch a non-trivial number of
> >> > packages anyway.
> >>
> >> Actually the forked packages now are pretty minimal. I think there's
> >> currently around a dozen, with the move the F11 that will be even
> >> less. The major fork is the kernel but other than that most of the
> >> forks are to slim down deps.
> >
> > Okay, ignore the bit about forked packages.  How's the rest of the
> > argument sound?
> 
> Sounds fine to me but I'm by no means an expert in compiler options
> for different architectures :-) What sort of a win would we see
> performance wise. Does it get done for all the packages or for just
> things like kernel/glibc/openssl like it currently does for some of
> the i386 packages?

Would be hard to know the performance win without trying it.  But since
you're already bootstrapped, a mass rebuild would "only" be a few days
on a reasonably fast machine.  It might be only a few percent of wall
clock performance, but depending how much RAM -Os saves, you might
thrash less, etc.  (Roughly the same arguments apply for any global
compiler changes, for that matter.)

Doing this as a secondary arch would mean all packages would get
rebuilt.

I'm only kind of serious about this, since we really don't have
secondary arch support yet.  But I think there's some merit in splitting
off sufficiently old (or subsetted) x86 from the real world.
Particularly if it means I can stop waiting for i586 kernels to build
just to get the i686 kernel I really want.

- ajax
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