On Mon, 2002-12-02 at 17:21, Christoph Hellwig wrote:
> On Fri, Nov 29, 2002 at 04:44:35PM -0800, Mike Anderson wrote:
> > Thanks for catching this Christoph I thought the only use was inside
> > SCSI. I could make a patch to scsi-misc to add tag back in. Another
> > option if it is still needed is to switch to "->name == "generic").
> >
> > Though I have not used this interface I thought if one was using
> > an sg
> > device to a ide-scsi device and the flag was set that sg
> > commands that
> > where not 100% the same as ATAP commands where translated.
>
> Well, imho IDESCSI_SG_TRANSFORM is broken in 2.5. Now that ever block
> driver implements the sg ioctls a sg request can come from sd or sr
> aswell.
Christoph,
Thanks for alerting me to the implementation (by Jens) of
the sg driver's SG_IO ioctl in drivers/block/scsi_ioctl.c .
It goes by the name SCSI_IOCTL_SEND_COMMAND which is the same
name as the old ioctl defined in drivers/scsi/scsi_ioctl.c .
As far as I can see if you send that ioctl to a block device
(including an ATA disk) you get the new functionality (i.e.
similar to sg's SG_IO). However if you send that ioctl to
a char device (e.g. st, osst or sg) you get the old
interface (i.e. as found in drivers/scsi/scsi_ioctl.c).
Somewhat confusing.
So old utilities like scsiinfo will now fail for disks
but continue to work for tapes.
I believe IDESCSI_SG_TRANSFORM translated 6 byte
MODE SENSE ** commands (mandatory in SCSI-2, 10 byte
MODE SENSE optional in SCSI-2) to 10 byte MODE SENSE
commands (mandatory in ATAPI, 6 byte MODE SENSE
commands optional (or not supported) in ATAPI). The
correct solution is to stop applications sending 6
byte MODE SENSE commands to CD/DVD writers. I don't
believe cdrecord uses the IDESCSI_SG_TRANSFORM
ioctl anymore. [Perhaps it comes from the cdwrite
days.]
** Equivalent translations for READ(6), WRITE(6) and
MODE_SELECT(6) command are done by the ide-scsi driver.
Doug Gilbert
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