Re: [PATCH] libata: write cache and read ahead

[Jeff Garzik <jgarzik@pobox.com>]

Christoph Hellwig wrote:
> On Tue, Aug 23, 2005 at 07:22:59PM -0400, Luben Tuikov wrote:
> 
>>On 08/22/05 01:12, Douglas Gilbert wrote:
>>
>>>I was surprised how much code needed changing.
>>>With MODE SELECT's issues with libata addressed
>>>various other SAT "extras" should be much easier
>>>to implement. That should make libata more attractive
>>>as a SAT layer for SAS LLDDs (that don't do it already
>>>in firmware).
>>
>>Doug, how about never needing a SAT layer for SAS LLDDs
>>for ATA/ATAPI devices.
>>
>>Would you object if I "give" you a "domain device" to which
>>you can send FISes (+ the packet if ATAPI) through
>>a SAM-4 intefrace: Execute Task + TMFs?
> 
> 
> Personally I think that would be nice, but when I mentioned the basic idea
> (sending FISes through BLOCK_PC block later commands and let the scsi layer
> handle then as vendor-specific commands) Jeff didn't like that because
> then we'd need a non-sd upper driver although using the scsi midlayer.


That's something different than when Luben was talking about.

Addressing what you [Christoph] are talking about, the block layer needs 
to grow a generic method for submitting device commands, be they ATA, 
SCSI, SCSI w/ variable-length CDB, I2O, Promise SX8 message, whatever. 
Stuff that into the request_queue, and the transport driver handles it 
from there.

	Jeff