On Fri, 2 Apr 2010, James Bottomley wrote: > > > Does the command sent by hdparm look familiar? Exactly, it is the > > > third ATA command (IDENTIFY DEVICE) we discovered earlier and caused > > > the drive to stall. > > > > That's nice to know. Other people have been reporting similar > > problems. Now we can tell where they come from. > > Yes ... I think we're starting to need to get a handle on all these > userspace random pokes which can disrupt (the admittedly badly written > and badly tested) devices which the kernel tries so hard not to upset. > > > > Does anyone know why the drive would not be able to cope with this > > > command? > > > > No idea. Except that it's probably not the drive's fault, but rather > > the fault of the USB-(S)ATA chip that controls the drive. > > Best guess (and it's a guess only) would be that the USB bridge SAT > layer doesn't implement ATA_16 and so fails in interesting ways when it > comes in. Does the ATA_12 version of IDENTIFY DEVICE succeed? It does. And in between the two is an ATA_16 SET FEATURES command which also (apparently) succeeds. That is, there is no error indication from the device -- but goodness knows if it actually carries out the command. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
