RE: The WHY's (RE: ide drive w/dma ... system crash)

BROWN Nick (Nick.BROWN@coe.int)
Tue, 11 May 1999 00:48:50 +0200


>I believe we could also generate a CHS blacklist, where the BIOS or
drive
>are known to return bogus geometries.

This would be _hard_ (and extremely unexciting). My QDI motherboard
returned the IDE drive data as hd0 until I upgraded from BIOS V2.2S to
V2.4S, since when it gives the SCSI drive geometry for hd0 - not the kind of
thing you want to keep track of. And I believe that this behaviour (which
Andries says is legitimate, anyway) only occurs because my SCSI controller
is based on the 53C810, which the motherboard explicitly supports via the
BIOS.

The real bogosity is partly in using data other than that returned by INT
13h (which might not be 100% perfect, but is more likely to be correct than
most); but also, in all the bits of historical code which (presumably due to
historical assumptions that 2 is the highest number of drives we'll meet)
work differently for drives 0 and 1 than for the others.

>The problem is that it needs to be moved to a high/different
location than
>ide-probe.c. There is a compile problem if ide is modular with
scsi
>default. Since this is currently limited to i386 arch, make a
suggestion
>of were to place this animal.
>As stated before, Andries work is part of the patch and reports for
IDE,
>but SCSI is stubbed out. Suggestion where it should go?

I'll go back to the code in the morning (eyes drifting shut here, it's 1 am)
and think about this.

Meanwhile, one piece of good news is that the Golf patch does a better job
than Foxtrot of running my IDE drive in the correct DMA mode. It came up
with "UDMA (33)", and all the hdparm tests work without having to tweak -c
and -d.

Nick Brown, Strasbourg, France (Nick(dot)Brown(at)coe(dot)int)

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