Date: Wed, 4 Nov 2009 17:06:00 +0100 From: Attilio Rao <attilio@freebsd.org> To: =?UTF-8?Q?Dag=2DErling_Sm=C3=B8rgrav?= <des@des.no> Cc: 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 Message-ID: <3bbf2fe10911040806l7293ab6l99cce51ea9d7a64c@mail.gmail.com> In-Reply-To: <863a4ugvmi.fsf@ds4.des.no> References: <200911040132.nA41WxtQ012750@svn.freebsd.org> <863a4ugvmi.fsf@ds4.des.no>
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2009/11/4, Dag-Erling Sm=C3=B8rgrav <des@des.no>: > Attilio Rao <attilio@FreeBSD.org> writes: > > Log: > > 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 uninvestigabl= e > > ways (for further explanation see at the content of the commit itself= ). > > According to the reference you gave, OpenSolaris has a workaround for > this issue. Perhaps we should adopt it? IIRC, based on what I readed on-line, it could be still a WARNING msg, but I didn't double-check for it. On the other side, a possible complete solution would involve a boot-time patching mechanism, but we don't have it right now (differently from Linux) or disabling the SMP support, but it seems mostly a too heavy loss of performance due to the rarely appearence of the bug itself. I think the WARNING msg is a good compromise to all these other approaches. Attilio --=20 Peace can only be achieved by understanding - A. Einstein
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