Date: Wed, 4 Nov 2009 13:49:41 +0100 From: Attilio Rao <attilio@freebsd.org> To: Ed Schouten <ed@80386.nl> 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: <3bbf2fe10911040449j5938ca7eqca5829ceced66f48@mail.gmail.com> In-Reply-To: <20091104055811.GY1293@hoeg.nl> References: <200911040132.nA41WxtQ012750@svn.freebsd.org> <20091104055811.GY1293@hoeg.nl>
next in thread | previous in thread | raw e-mail | index | archive | help
2009/11/4 Ed Schouten <ed@80386.nl>: > 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. Due to the semantic of the bug, I think that it can manifest itself on UP and a memory barrier failing on UP means that PREEMPTION can blow up. Considering this I wouldn't suggest anything different between the UP vs SMP case. Attilio -- Peace can only be achieved by understanding - A. Einstein
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3bbf2fe10911040449j5938ca7eqca5829ceced66f48>