Re: Is 386 processor still supported?

From: Andrey Panin
Date: Fri Jan 16 2009 - 06:55:54 EST


On 016, 01 16, 2009 at 10:00:02AM +0100, Pavel Machek wrote:
> >
> > * 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 ;-).

It's not so difficult BTW, i386EX CPUs are still used in embedded world.
Example: http://www.embeddedarm.com/products/board-detail.php?product=TS-3300
It even has ethernet and price is reasonable (for embedded board of course) :)

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