From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: [RFC] remove IDESCSI_SG_TRANSFORM (compile fix) Date: Tue, 03 Dec 2002 18:20:44 +1100 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <3DEC5B4C.4040208@torque.net> Reply-To: dougg@torque.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: List-Id: linux-scsi@vger.kernel.org To: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org 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