jgarzik at pobox.com
Thu Aug 12 21:57:03 PDT 2004
* From the T10 Reflector (t10 at t10.org), posted by:
* Jeff Garzik <jgarzik at pobox.com>
(please read my reply timestamped 00:48am EST, before this one)
Curtis Stevens wrote:
> One thing to keep in mind is that we do not want the bridge to look
> at the command code or any other register. We want SCSI to be a blind
> tunnel to the ATA device. The bridge should not look at the command code,
> sector count, or any other part of the register set. This is what makes it
> work for standard and vendor specific commands. It also makes it so new
> commands can be implemented without changing the bridge. This is why length
> is also important.
I do agree 100% with this.
I thought of an additional point, relating to this, while I was driving
through the rain tonight (hello Hurricane Bonnie):
One of the key values of SAT to my user base is the leverage of
_existing_ SCSI application software. Particularly, I wish to use this
ATA passthru CDB via pre-existing SCSI system call methods (ioctl).
As such, there is no opportunity for me to add an ATA-specific
command-protocol field to Linux's submit-a-SCSI-command system call. I
have only the SCSI CDB, transfer length, and transfer direction to work
with. Any ATA specifics _must_ be encapsulated within the ATA passthru CDB.
I think my need fits nicely with your "blind SCSI tunnel to ATA device"
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org
More information about the T10