linux-kernel - Re: [patch 2/2] x86 amd fix cmpxchg read acquire barrier

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Message-ID: <20090502155514.GA18847@Krystal>
Date:	Sat, 2 May 2009 11:55:14 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	Pavel Machek <pavel@....cz>
Cc:	akpm@...ux-foundation.org, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, mark.langsdorf@....com,
	arekm@...en.pl, "H. Peter Anvin" <hpa@...or.com>,
	Andi Kleen <andi@...stfloor.org>, Avi Kivity <avi@...ranet.com>
Subject: Re: [patch 2/2] x86 amd fix cmpxchg read acquire barrier

* Pavel Machek (pavel@....cz) wrote:
> On Wed 2009-04-22 16:18:54, Mathieu Desnoyers wrote:
> > http://google-perftools.googlecode.com/svn-history/r48/trunk/src/base/atomicops-internals-x86.cc
> > 
> > says
> > 
> > "  // Opteron Rev E has a bug in which on very rare occasions a locked
> >   // instruction doesn't act as a read-acquire barrier if followed by a
> >   // non-locked read-modify-write instruction.  Rev F has this bug in 
> >   // pre-release versions, but not in versions released to customers,
> >   // so we test only for Rev E, which is family 15, model 32..63 inclusive.
> 
> Could we be more careful  here and catch the F pre-release versions,
> too? Stepping should help there...
> 

Yes, I guess for F pre-releases we're stucked unless AMD provides more
information. Dtrace did not seem to bother about F pre-release versions
though, neither did Google.

Mathieu

> -- 
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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