From mboxrd@z Thu Jan  1 00:00:00 1970
From: jmk@plan9.bell-labs.com
Message-Id: <200007280258.WAA06151@cse.psu.edu>
Date: Thu, 27 Jul 2000 22:58:33 -0400
To: 9fans@cse.psu.edu
Subject: Re: [9fans] dual CPU machine hungs?
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Kenji has an old Neptune chipset based motherboard, similar to
the one I used to write the MP code a long time ago (he has an
ASUS PCI/I-P54NP4D, I have a PCI/E-P54NP4D, now hanging on the
wall in my office). The Neptune chipset had a number of problems
with busmastering and various BIOS settings had to be used to
disable broken PCI/EISA features. But Kenji doesn't have any
busmastering devices.

The second problem with Pentium MP systems is matching the processor
steppings, there are some steppings which just won't do MP properly
and some which will only work when matched with another suitable CPU.
I've asked Kenji to try to check the steppings against the errata list
(unfortunately it means yanking the chip out of the socket to look
underneath for the stepping numbers).

The only time I've seen APIC errors was on flakey hardware. The
recovery code in the kernel may not be up to snuff as it hasn't been
exercised much, but you really should never get APIC errors.

--jim