All, Please ignore. the code is there (see ata_id_rotation_rate()), I just missed it somewhere along the line. I'm still walking thru it, so I'm not sure of the details. === detail if you care The most recent update is for 2.6.37 and it introduced the first quirk. eg. The new flag is ATA_HORKAGE_NONROT which indicates a pre-ATA8 device that is a SSD. http://patchwork.ozlabs.org/patch/63414/ In theory, SSDs should report ATA8 and use field 217 as I said. That logic is also already present. But it looks to me that ata_id_rotation_rate() is trusting that field for ATA7 as well, which I don't understand. Also, it seems to be reported to userspace through a SCSI command simulation, which is probably fine, but I was looking for it in /sys/block. To me it seems inconsistent to have the topology abi in /sys/block, but the rotating vs. ssd abi via a scsi command emulation. :( Greg On Mon, Jan 3, 2011 at 2:21 PM, Greg Freemyer <greg.freemyer@xxxxxxxxx> wrote: > All, > > I don't think the kernel is yet tracking SSD vs Rotational. > > It would be a nice patch if someone would do that. I don't maintain > the subsystem, but I assume it would be accepted if well done. You > could model your patch by looking at how the drive topology patches > were done. Effectively this patch would do the same thing. > > (Petersen wrote those, so I think these are them: > http://markmail.org/message/azj3z4tofrknnbbe) > > My thoughts: > > ===> How to tell > > For SATA: > > Per T13/1699-D Revision 4a (from May 2007) word 217 of the identify > block should be populated with a "1" to identify non-rotating media. > > http://www.t13.org/Documents/UploadedDocuments/docs2007/D1699r4a-ATA8-ACS.pdf > > IIRC: The identify block is read during drive query time, so you > should not have to actually generate any i/o. Just patch the portion > of the kernel working with the identify block. ie. See the topology > patch. > > For SCSI - no idea, but I'd be surprised if they did not already have > a scsi flag for it. The topology patch also handled SCSI, so it's > just a matter of finding the scsi field to use. > > ===> Quirks > > Lots of manufacturers don't follow the specs on something like this, > so a quirks functionality is typically how the ATA driver handles it. > ie. If you find a SSD that is not setting the flag, then setup a quirk > to override the flag. The quirk table should be based on make & model > at a minimum, and maybe firmware. > > You should be able to find existing quirk logic, so don't invent your own. > > SCSI seems to be followed much more accurately, so you may not need a > quirks functionality for it. > > ===> userspace API > > Seems like there should be a "/sys/block/sda/*" file that allows > userspace to interrogate. The topology patches added a few of these, > so one more would be good. > > If you can generate the same data for scsi, maybe just create > /sys/block/sda/rotation_speed and have it just reflect exactly word > 217 of the identify block. > > Greg > -- Greg Freemyer Head of EDD Tape Extraction and Processing team Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer CNN/TruTV Aired Forensic Imaging Demo - http://insession.blogs.cnn.com/2010/03/23/how-computer-evidence-gets-retrieved/ The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
