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Date: Wed, 04 Nov 2009 15:57:59 -0700 (MST)
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To: ed@80386.nl
From: "M. Warner Losh" <imp@bsdimp.com>
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Cc: attilio@FreeBSD.org, svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org,
	src-committers@FreeBSD.org
Subject: Re: svn commit: r198868 - in head/sys: amd64/amd64 i386/i386
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In message: <20091104055811.GY1293@hoeg.nl>
            Ed Schouten <ed@80386.nl> writes:
: Hi Attilio,
: 
: * Attilio Rao <attilio@FreeBSD.org> wrote:
: > Opteron rev E family of processor expose a bug where, in very rare
: > ocassions, memory barriers semantic is not honoured by the hardware
: > itself. As a result, some random breakage can happen in uninvestigable
: > ways (for further explanation see at the content of the commit itself).
: 
: Ooh. Sounds like an interesting bug.
: 
: The bug doesn't manifest itself on UP, right? If so, maybe we should add
: some very short instructions to the warning on how to disable SMP.

Or better yet: disable it unless specifically enabled...

Warner