On Fri, 27 Oct 2006, Douglas Gilbert wrote: > Some more information on this subject: LLDs (including > pseudo ones like usb-storage) really should set the > Scsi_Cmnd::resid field to show, in the case of an > INQUIRY, when 36 bytes were requested, less bytes > were returned. Indeed. usb-storage does do this. However the devices addressed by this patch do send 36 bytes of data, all apparently plausible, just as you say directly-attached ATA disks do. So checking the residue wouldn't help. > That OS from Redmond may have a hand here as well. > Directly attached ATA disks are found in SCSI scans and > respond to SCSI INQUIRY commands with plausible vendor, > model and revision strings but the additional length > field (byte 4 in the response) is set to 0. So code > could use that as a hint to stop sending further SCSI > commands and start sending ATA commands. ATA disks > behind USB and IEEE 1394 don't appear in SCSI scans > but do appear as "Physical Drives" and do respond > to SCSI INQUIRY commands properly. I don't understand this. What do you mean, they don't appear in SCSI scans? They _are_ detected by scsi_probe_lun(). But they probably don't show any special ATA signature in the INQUIRY data, since that data is generally determined by the firmware in the USB/1394 interface. > Then there are > ATA disks behind a SATL and they respond to SCSI > INQUIRY commands (and most others) properly; the > easiest way to spot them is that the vendor is "ATA ". > > Doug Gilbert Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
