Messages in this thread | | | Date | Thu, 15 Jan 2009 15:17:34 +0100 | From | Ingo Molnar <> | Subject | Re: Is 386 processor still supported? |
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* 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 ...
Ingo
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