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SubjectRe: Is 386 processor still supported?
> 
> * Maciej W. Rozycki <macro@linux-mips.org> wrote:
>
> > On Thu, 15 Jan 2009, Alan Cox wrote:
> >
> > > > UP emulation of CMPXCHG and XADD for userland should be rather trivial,
> > > > so why not include it like with LL/SC for MIPS?
> > >
> > > Why not just ship an additional libc with the right options ?
> >
> > Does not work for MIPS as glibc has no equivalent code for pre-LL/SC
> > CPUs and LL/SC is always used. For the i386 the situation seems worse
> > yet as for pre-i486 CPUs a generic C implementation of
> > compare-and-exchange is used guaranteeing silent thread unsafety. :(
> >
> > IMO, a kernel emulation of CMPXCHG and XADD (both are used by
> > sysdeps/i386/i486/bits/atomic.h in glibc) with an optional LOCK prefix,
> > guaranteeing UP atomicity would be a cheap way to provide long-term i386
> > userland support with little burden for both Linux and respective user
> > software maintainers. Certainly it adds some bloat to the kernel, but I
> > think it is not an option that should be outright dismissed without
> > consideration.
>
> patches are welcome ...

Hehe, I guess the only long-term solution is to get shiny old 386 as a
part of Ingo's test farm ;-).
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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