Re: Is 386 processor still supported?

[Pavel Machek]

> 
> * Maciej W. Rozycki <macro@xxxxxxxxxxxxxx> 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
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