From: Ingo Molnar <mingo@elte.hu>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Jan-Benedict Glaw <jbglaw@lug-owl.de>,
Peter Zijlstra <peterz@infradead.org>,
Jiri Kosina <jkosina@suse.cz>, Adam Osuchowski <adwol@zonk.pl>,
linux-kernel@vger.kernel.org, Nick Piggin <npiggin@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: Is 386 processor still supported?
Date: Thu, 15 Jan 2009 15:17:34 +0100 [thread overview]
Message-ID: <20090115141734.GA15732@elte.hu> (raw)
In-Reply-To: <alpine.LFD.1.10.0901151353530.5737@ftp.linux-mips.org>
* 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
next prev parent reply other threads:[~2009-01-15 14:18 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-08 12:03 Is 386 processor still supported? Adam Osuchowski
2009-01-08 13:05 ` Jiri Kosina
2009-01-08 13:24 ` Cyrill Gorcunov
2009-01-08 13:48 ` Jiri Kosina
2009-01-08 14:13 ` Peter Zijlstra
2009-01-08 14:21 ` Jiri Kosina
2009-01-08 14:27 ` Peter Zijlstra
2009-01-08 15:04 ` Alan Cox
2009-01-08 15:10 ` Ingo Molnar
2009-01-13 1:06 ` Maciej W. Rozycki
2009-01-15 12:36 ` Jan-Benedict Glaw
2009-01-15 13:22 ` Maciej W. Rozycki
2009-01-15 13:32 ` Alan Cox
2009-01-15 14:15 ` Maciej W. Rozycki
2009-01-15 14:17 ` Ingo Molnar [this message]
2009-01-16 9:00 ` Pavel Machek
2009-01-16 10:13 ` Jan-Benedict Glaw
2009-01-16 11:18 ` Andrey Panin
2009-01-16 13:46 ` Ingo Molnar
2009-01-16 18:17 ` H. Peter Anvin
2009-01-15 14:20 ` Jan-Benedict Glaw
2009-01-15 14:37 ` Bastien ROUCARIES
2009-01-15 14:25 ` Alan Cox
2009-01-15 14:44 ` Maciej W. Rozycki
2009-01-15 20:11 ` H. Peter Anvin
2009-01-15 14:46 ` Jan-Benedict Glaw
2009-01-08 16:45 ` Sam Ravnborg
2009-01-08 16:27 ` Andi Kleen
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