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Date:      Wed, 30 Jul 1997 16:33:28 -0400 (EDT)
From:      john hood <cgull@smoke.marlboro.vt.us>
To:        nnd@itfs.nsk.su
Cc:        Michael Smith <msmith@atrad.adelaide.edu.au>, current@FreeBSD.ORG
Subject:   Re: code talks:  announcing EIDE bus master patches
Message-ID:  <199707302033.QAA04812@smoke.marlboro.vt.us>
In-Reply-To: <199707301321.WAA22357@genesis.atrad.adelaide.edu.au>
References:  <5rncuo$sp8@news.itfs.nsk.su> <199707301321.WAA22357@genesis.atrad.adelaide.edu.au>

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Michael Smith writes:
 > nnd@itfs.nsk.su stands accused of saying:
 > 
 > > And the next one - when I try to set flags on wcd0 to '0xa0ffa0ff'
 > > the system can't start - I receive:
 > > panic - can not mount root (?) message.
 > > 	Is there any possibility to avoid this panic and
 > > fall back to PIO-mode ?
 > 
 > We would need the 'wd*' section of the boot probe to have any chance
 > of answering that.  It's also possible that you're the first SMP user 
 > to have tried this (?).

Actually, send the messages from a verbose boot (unfortunately, all
that text sometimes overflows the dmesg buffer and screen scrollback).
Also, what motherboard do you have, and what BIOS is installed on it?

Does the kernel panic instantly on trying to mount root, or does it
flail for a while and spew any error messages from wd?

More details will help.  There's some sanity checks I forgot to
include in the code and this may flush one of them out.

It *should* fall back to PIO if DMA mode doesn't work.  To disable DMA
entirely, unset bit 0x2000 in the flags for each drive.  The PCI probe
still happens but the wd driver will never use any of that info.

  --jh

-- 
John Hood				cgull@smoke.marlboro.vt.us

Predictably, they all eventually wandered away, rubbing their bruises
and brushing mud out of their hair.  Some went off to work for the
ESA, launching much smaller rockets into low orbits, while others
elected to sit on their front porches drinking Jim Beam from the
bottle and launching bottle rockets from the empties. [Jordan Hubbard]




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