Date: Fri, 22 Nov 2002 22:54:07 -0700 From: "Kenneth D. Merry" <ken@kdm.org> To: current@FreeBSD.org Subject: call for testers: cd(4) mode sense/mode select patches Message-ID: <20021122225407.A65917@panzer.kdm.org>
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Here are patches against -current and -stable to add automatic detection of CDROM drives that can't handle 6 byte mode sense and mode select: http://people.FreeBSD.org/~ken/scsi_cd.cmdsize.20021122 http://people.FreeBSD.org/~ken/scsi_cd.cmdsize.stable.20021122 These new patches fix a data corruption bug in the last set that would likely cause a panic. These patches also change the way the da(4) driver handles the no_6_byte sysctl. There is now a per-drive sysctl to set the minimum command size for that particular disk. (Since you could have multiple disks with multiple requirements in one system.) I have also added loader tunable support for all the sysctls in the da(4) and cd(4) drivers. Finally, I've disabled MODE_SENSE and MODE_SELECT translation in ATAPICAM in both -current and -stable, and in the umass(4) driver in -current, since there's no way for that to work properly (see below). (Translation hasn't been MFCed for umass(4) yet, thus the reason I didn't change it in -stable.) I'd appreciate it if folks could test this, especially people with CDROM drives running via usb, firewire, or ATAPICAM, but also people with older SCSI CDROM drives. To test this, apply the patch (for -current or -stable as appropriate) and do the following: cdcontrol status cdcontrol info cdcontrol play (make sure audio comes out) cdcontrol next (make sure it skips to the next track here) If you get an error in response to 'cdcontrol next', definitely let me know what kind of drive you have (dmesg is fine) and how it is hooked up (SCSI, firewire, ATAPICAM, usb, etc.). The SCSI-2 PLAY_TRACK command has apparantly been deprecated in the MMC specs, so some drives don't support it. I'd like to get a handle on which ones do and don't, if possible. (The work around isn't hard, but isn't in this patch.) Reports of success or failure are welcome. ======= Now for more details.... When we get an illegal request in response to a 6 byte mode sense or mode select, we reformat the command to be a 10-byte mode sense or mode select and reissue it. These patches also work with drives that do not return block descriptors (even when dbd is 0 in the mode sense command), and drives that return multiple block descriptors. (They work better with the former than the latter; with the latter, they mostly just bail out.) While commands like READ(6) and WRITE(6) can be translated down in the SIM driver, like the ATAPICAM and usb code do, MODE_SENSE(6) and MODE_SELECT(6) cannot be translated, because the 10-byte version of the parameter list is longer. This means that when, e.g., a MODE_SENSE(6) command is translated to a MODE_SENSE(10) command, the page will likely be truncated (unless more space is allocated than needed), and since the peripheral driver code isn't expecting the returned data to be in MODE_SENSE(10) format, it'll be looking in the wrong place for the mode page. The SIM drivers have no way of knowing how long the buffer is that they've been given for a mode sense or mode select, so they can't just up the dxfer_len, change the CDB and call it good. The only way to do translation effectively for these two commands is where the buffer was originally allocated -- in the peripheral driver. So I have implemented translation and 10-byte mode sense and mode select for the cd(4) driver. Why do translation? Why not just default to 10-byte commands? Because some SCSI CDROM drives, maybe quite a few, don't support 10 byte mode sense and mode select. (The 8x Plextor in my test box doesn't, for example.) The right way to do this, eventually, is with the CAM_NEW_TRAN_CODE. 6byte/10byte can be a function of the protocol, and we can hopefully select the right size command up front. It will take a lot of infrastructure work to make it happen, but that functionality will hopefully solve several problems. Since translation won't work at the SIM level, I have disabled MODE_SENSE(6) and MODE_SELECT translation in ATAPICAM and umass(4). Comments are welcome on the patches; they're more complicated than I would like, but unfortunately that complication seems necessary to get the desired functionality. Many thanks to David Kleiner <kleiner@panix.com> for testing multiple iterations of these patches, he has been a big help. Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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