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SubjectRe: sata_nv and 2.6.24 (was Re: fixed a bug of adma in rhel4u5 with HDS7250SASUN500G.)
Robert Hancock wrote:
> Jeff Garzik wrote:
>> Ping... sata_nv status is still a bit open for 2.6.24, and I would
>> like to move us forward a bit.
>>
>> * Kuan's patch... it has been confirmed (and is needed), correct?
>> can someone work up a good patch for 2.6.24? The only one I ever
>> received was badly word-wrapped, and at the time, Robert seemed
>> uncertain of it, so I waited.
>
> I can get you one later today hopefully.
>
>>
>> * ADMA ATAPI 4GB issues... playing tricks with the ordering of
>> allocations and DMA masks is just way too fragile. We just cannot
>> guarantee that all allocators work that way. The obvious solution to
>> me seems to be hardcoding the consistent DMA mask to 32-bit, but using
>> 64-bit for regular dma mask if-and-only-if ADMA is enabled.
>
> That's not enough to fix the problem since there's issues with actual
> transfer data being allocated above 4GB as well, not just the consistent
> allocations (it appears that blk_queue_bounce_limit setting to 32-bit
> doesn't prevent this on x86_64). Either we play some funky games with
> changing the DMA mask of the entire device to 32-bit if either port is
> in ATAPI mode (which blew up when I tried it) or we add the ability to
> set the DMA mask independently on each port (like by setting the mask on
> the SCSI device and using that for DMA mapping instead) which requires
> core changes.

Its all funky games that no other driver is doing... There is one
guaranteed to work scenario -- set all masks and bounce limits etc. to
32-bit. There is also one highly-likely-to-work scenario, disabling
ADMA by default.


>> * it sure seems like there are other open sata_nv ADMA issues -- can
>> we hard-confirm or deny this? bugzilla wasn't very helpful for me.
>> It doesn't seem like we can disable ADMA (to solve those issues) and
>> get enough test time in (which is what I said a week (or more?) ago
>> too...)
>
> The NCQ/non-NCQ command switching issue is still hitting some people
> (last I heard Kuan was looking into this), also there's a hotplug issue
> that Tejun reported..

The former implies we need to disable swncq for 2.6.24, if it's not
stable yet.

Jeff




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