Date: Sat, 25 Oct 1997 13:59:50 -0700 From: "Jordan K. Hubbard" <jkh@time.cdrom.com> To: jak@cetlink.net (John Kelly) Cc: dwhite@resnet.uoregon.edu, hackers@FreeBSD.ORG Subject: Re: 48 meg double fault moved to 64 meg in 2.2.5 Message-ID: <18145.877813190@time.cdrom.com> In-Reply-To: Your message of "Sat, 25 Oct 1997 14:24:29 EDT." <dljU0Y9zBc5e091yn@cetlink.net>
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> With 64 meg and 2.2.5, the problem disappeared. But with 48 meg > and 2.2.2 it had no effect, and the double fault still occurred. > I'm guessing that's because the BIOS does not try to create that > DRAM hole unless you fill the board with 64 meg of memory -- as > they do say in parentheses "(64MB)." Hmmm. Bizarre. Ick. > The memory test failure after a reboot may happen because this > motherboard does not have address line 26 wired to the chipset, > and thus anything over 64 meg cannot be addressed properly. You know, christmas is coming up and a new Tyan motherboard would probably not be that expensive. ;-) > Is it true that this problem only occurs with the boot floppy? Correct. > The last good message I see with the 2.2.2 boot floppy and 48 > meg is "changing root device to fd0c," and then immediately the > "panic: double fault" appears. Yep, that sounds like the problem we've seen alright. Never did find it in 2.2.2 and, now that it's mysteriously moved itself, are going to have Even More Fun(tm) trying to track it down in 2.2-stable. I'm sure that it's going to turn out to be something in the D'OH! category when found. > Since floppy controllers use DMA, perhaps DMA and the bounce > buffers are an issue? Addressing memory remapped above 64 meg > may also be part of the problem, at least on this motherboard. I suppose I could always build you a boot floppy without bounce buffering, just to see what effect it has, but that wouldn't do your Buslogic controller any good at all during an actual installation. ;-) Jordan
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