Subject: Re: NMI on Compaq 1850R
To: Chris Ross <email@example.com>
From: David Laight <firstname.lastname@example.org>
Date: 01/20/2007 23:07:59
On Sat, Jan 20, 2007 at 12:35:37PM -0500, Chris Ross wrote:
> On Jan 20, 2007, at 12:12, Chris Ross wrote:
> > The aforementioned "patch" I am now running with simply removes
> >the PCI_PRODUCT_INTEL_82443BX_AGP & PCI_PRODUCT_INTEL_82443BX_AGP
> >case starting near line 193 of pchbattach(). This is noted to be a
> >"BIOS BUG WORKAROUND". But, at least for my machine (pchb0: Intel
> >82443BX Host Bridge/Controller (AGP disabled) (rev. 0x03)), this
> >"workaround" causes the machine to get an NMI fairly easily.
> Ahh! I think I figured this out. According to a specification
> update from Intel (available from http://www.intel.com/design/
> chipsets/specupdt/290639.htm ), it looks like this "issue" was
> present in steppings A0, B0, and B1, but *not* C0 or C1. (ref.
> 'IPDTL Bit Setting' in table on PDF doc page #9) So, "rev 0x03",
> which my machine has, is stepping C1, and therefore the recommended
> workaround should not apply.
What value does your bios set these bits to ?
From reading your mails (I've not looked at the Intel specs) it looks
as though the 2 bits modify the number of clocks in some part of the
DRAM memory cycle.
So I presume that changing them to 01 shortens the DRAM timings, which
probably causes memory errors when you populate all 4 memory slots
due to the additional capacitive load on the memory bus requiring
more relaxed timing.
David Laight: email@example.com