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Subjectmore DMA puzzlement
I've been doing some more tests on my system to try to get a better idea
of what triggers the problems I'm having with my Gravis Ultrasound and
my new Buslogic 545C SCSI card.

I was able to do this:

dd if=/dev/sda of=/dev/null bs=1024k count=1024

running ten concurrent invocations, staggered so they didn't all just
read from each other's buffers, for over 40 minutes without triggering a
reinitialization of my SCSI card.

However, if I did this:

dd if=/dev/zero of=foo bs=1024k count=128

it took only about three sequential invocations before I triggered the
SCSI card reinitialization.

So it looks like there's something wrong with my system in terms of
doing DMA reads, or in CPU-centric terms, device writes through DMA
devices.

What I'm really interested in is if there is any way to kludge around
this problem.


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