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    SubjectRe: Is 386 processor still supported?
    On Thu, Jan 15, 2009 at 3:20 PM, Jan-Benedict Glaw <> wrote:
    > On Thu, 2009-01-15 14:15:56 +0000, Maciej W. Rozycki <> 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.
    > I just searched for the old patch, but couldn't find it ad hoc. (But
    > it must be somewhere, at least in the archives, I guess?)

    here, but should be
    securized (use get_user() )


    > The kernel emulator has the benefit of no overhead when not switched
    > on, and low-to-no overhead when not being used (i386 capable kernel on
    > i486 hardware).
    > Heck, I'd dig out my two test systems and give them a try with current
    > Debian unstable. Should be fun with four to eight megabytes of RAM.
    > MfG, JBG
    > --
    > Jan-Benedict Glaw +49-172-7608481
    > Signature of: 23:53 <@jbglaw> So, ich kletter' jetzt mal ins Bett.
    > the second : 23:57 <@jever2> .oO( kletter ..., hat er noch Gitter vorm Bett, wie früher meine Kinder?)
    > 00:00 <@jbglaw> jever2: *patsch*
    > 00:01 <@jever2> *aua*, wofür, Gedanken sind frei!
    > 00:02 <@jbglaw> Nee, freie Gedanken, die sind seit 1984 doch aus!
    > 00:03 <@jever2> 1984? ich bin erst seit 1985 verheiratet!
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    > =wHyn
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