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SubjectRe: SATA exceptions with 2.6.20-rc5
Björn Steinbrink wrote:
>> My latest bisection attempt actually led to your sata_nv ADMA commit. [1]
>> I've now backed out that patch from 2.6.20-rc5 and have my stress test
>> running for 20 minutes now ("record" for a bad kernel surviving that
>> test is about 40 minutes IIRC). I'll keep it running for at least 2 more
>> hours.
>
> Yep, that one seems to be guilty. 2.6.20-rc5 with that commit backed out
> survived about 3 hours of testing, while the average was around 5
> minutes for a failure, sometimes even before I could log in.
> I took a look at the patch, but I can't really tell anything.
> nv_adma_check_atapi_dma somehow looks like it should not negate its
> return value, so that it returns 0 (atapi dma available) when
> adma_enable was 1. But I'm not exactly confident about that either ;)
> Will it hurt if I try to remove the negation?

It should be correct the way it is - that check is trying to prevent
ATAPI commands from using DMA until the slave_config function has been
called to set up the DMA parameters properly. When the
NV_ADMA_ATAPI_SETUP_COMPLETE flag is not set, this returns 1 which
disallows DMA transfers. Unless you were using an ATAPI (i.e. CD/DVD)
device on the channel this wouldn't affect you anyway.

I'll try your stress test when I get a chance, but I doubt I'll run into
the same problem and I haven't seen any similar reports. Perhaps it's
some kind of wierd timing issue or incompatibility between the
controller and that drive when running in ADMA mode? I seem to remember
various reports of issues with certain Maxtor drives and some nForce
SATA controllers under Windows at least..

--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

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