Messages in this thread | | | Date | Thu, 15 Jan 2009 15:37:12 +0100 | From | "Bastien ROUCARIES" <> | Subject | Re: Is 386 processor still supported? |
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On Thu, Jan 15, 2009 at 3:20 PM, Jan-Benedict Glaw <jbglaw@lug-owl.de> wrote: > On Thu, 2009-01-15 14:15:56 +0000, 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. > > 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 http://thread.gmane.org/gmane.linux.kernel/205839, but should be securized (use get_user() )
Regards
> 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 jbglaw@lug-owl.de +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! > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.6 (GNU/Linux) > > iD8DBQFJb0Y/Hb1edYOZ4bsRAnEeAJ9JkaqmDFOGp1uPNzBe4qeSgl19dQCeI123 > c4oTq/pPCaUPcdJp3a/GsbU= > =wHyn > -----END PGP SIGNATURE----- > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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