peter at wemm.org
Mon Feb 23 09:24:45 PST 2004
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 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 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 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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