Opteron ECC

Peter Wemm peter at wemm.org
Sun Feb 22 22:51:03 PST 2004

On Sunday 22 February 2004 10:33 pm, James Van Artsdalen wrote:
> > From: Peter Wemm <peter at 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
> 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. :-)

Peter Wemm - peter at wemm.org; peter at FreeBSD.org; peter at yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5

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