On 02/03/2014 10:58 PM, Jeremy Linton wrote: > On 2/3/2014 2:51 PM, Kay Sievers wrote: >> This is not simple and not going to happen. Sibling devices in /sys cannot >> have a relationship in udev, there are only parent/child dependencies. > > Ok.. so if we can't ignore all the "spare" device nodes in a given /sys entry > for a given device. Why open the device to scan it? > > I've often wondered why the serial number isn't part of the data in /sys > along with the manufacture/model. The last tape drive I saw that failed to > respond to inquiry page 0x80 was over a decade ago (probably manufactured in > the early 90s). So enabling it just for tape is pretty safe. > > > Matching Manufacturer/model/serial is going to be better than anything your > going to get out of 0x83 anyway. That data is guaranteed to be there, but its > also guaranteed to be unreliable (every device, and every port has a slightly > different set of descriptors they choose to support). > > Plus, your not going to have issues accidentally rewinding a device, or > resetting a tape density, or accidentally turning compression off if you don't > open the device. > And indeed, I have been wondering about this, too. And (again) it is something which has been on my To-Do list for a long time. Moving EVPD page 0x83 (and maybe 0x80, too) into sysfs will save quite a lot of headache we have currently; udev won't have to call 'sg_inq', information will be present even though the device itself might be temporarily unavailable yadda yadda. So I've decided to bite the bullet and sent out a patch, check for 'Add EVPD page 0x83 entries to sysfs'. Reviews are welcome. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- 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
