Date: Mon, 23 Feb 2004 09:24:41 -0800 From: Peter Wemm <peter@wemm.org> To: freebsd-amd64@freebsd.org Cc: James Van Artsdalen <james@jrv.org> Subject: Re: Opteron ECC Message-ID: <200402230924.42159.peter@wemm.org> In-Reply-To: <200402222251.02612.peter@wemm.org> References: <200402230501.i1N51NB0049544@bigtex.jrv.org> <200402230633.i1N6X0DB069241@bigtex.jrv.org> <200402222251.02612.peter@wemm.org>
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On Sunday 22 February 2004 10:51 pm, Peter Wemm wrote: > On Sunday 22 February 2004 10:33 pm, James Van Artsdalen wrote: > > > From: Peter Wemm <peter@wemm.org> > > > Date: Sun, 22 Feb 2004 21:47:13 -0800 > > > > > > On Sunday 22 February 2004 09:01 pm, James Van Artsdalen wrote: > > > > It turns out that AMD has published its Opteron errata sheet > > > > and errata item 101 appears to be the issue: a bug in the > > > > Opteron means you can't have both "node interleave" and ECC > > > > scrubbing on at the same time. > > > > > > Oh my, thats bit of a stinker. Do you recall which steppings > > > this applies to? > > > > > > BTW; I suspect you might find that node interleave is more useful > > > (speed wise) than ecc background scrubbing. But I guess that > > > depends on what you want.. If you're trying to wring every bit > > > of performance out of it, pick node interleave over scrubbing. > > > On the other hand, if you'd perfer to have the system constantly > > > checking that the ECC ram is ok and you're not so worried about > > > speed, then pick scrubbing. > > > > The errata list is here: > > http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_ > >do cs/25759.pdf > > > > Bug 101 affects both B3 and C0 steppings. > > > > A word for people reading processor errata for the first time: > > here's a comment I made on another list: > > > > This errata list may look gruesome to those not used to such > > things, but it's not bad at all. I dealt with processor errata > > lists from Intel for years as a PC designer - the > > double-secret-NDA lists - and this is par for the course, perhaps > > even cleaner than usual. > > Yes. I've read the public ("these are the ones we admit to") lists > from intel and those were scary enough. > > > It might not hurt to add a line of code to the kernel to check for > > these steppings, node interleave and scrubbing, and print a warning > > if all three are met. > > Yes. I think a warning is in order, at the very least. Checking for > errata and steppings has been on my todo list for a while. At least > this time I've got around to printing the errata list. :-) I read the full errata list last night. There are a couple that we definately need to add workarounds for. Especially the ones that can cause a 32 bit compatability app to branch outside of its 32 bit address space. :-) -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5
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