[t13] SCSI ATA f/w revision bytes how many
Jeff Garzik
jgarzik at pobox.com
Tue May 25 13:49:31 PDT 2004
* From the T10 Reflector (t10 at t10.org), posted by:
* Jeff Garzik <jgarzik at pobox.com>
*
Pat LaVarre wrote:
>> The only thing I care about is the 16-byte CDB limit currently in
>> Linux...
>
>
> If we take advantage of the extra four bytes there, we will not design a
> solution usable by the max-12-CDB-byte connections, in particular normal
> PATAPI, that also wish to give ATA pass thru to hosts that think they
> support only SCSI pass thru. Those people will therefore push to
> revisit this issue, yet again.
No. I think you are missing some context...
This opcode is used to tunnel through a _fake_ SCSI layer to reach a
real ATA device behind it.
ATAPI does not come into play here. This "ata passthru" opcode is only
needed for ATA. For ATAPI, one does not need to pass through a fake
SCSI layer, but rather avoid the hardware device's SCSI layer and talk
directly to ATA. Subtle difference... but substantial.
Jeff
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