On Sat, 30 Aug 2014, Douglas Gilbert wrote: > On 14-08-30 05:15 PM, Alan Stern wrote: > > On Fri, 29 Aug 2014, Matthew Dharm wrote: > > > >> Is there an 'easy' way to override the detected size of a storage > >> device from userspace? If we had that, someone could write a helper > >> application which looked for this particular fubar and try to Do The > >> Right Thing(tm), or at least offer the user some options. > > > > You mean, force a Media Change event and override the capacity reported > > by the hardware? I'm not aware of any API for doing that, although it > > probably wouldn't be too hard to add one. > > > > How would the user know what value to put in for the capacity? Unless > > the drive had been hooked up to a different computer and the user > > manually noted the correct capacity and typed it in, it would have to > > be guesswork. > > Might another possibility be using the SAT layer to issue > the appropriate ATA command via the SCSI ATA PASS-THROUGH > (12 or 16) command to find out the disk's size. That might work. Not all USB mass-storage devices support ATA pass-through but some of them do. > This might > be a possible strategy if READ CAPACITY(10) yields 0xffffffff > for the last sector's LBA and the follow-up READ CAPACITY(16) > fails or yields a truncated value. Yes. The problem in this case is that READ CAPACITY(10) yields a reasonable value (not 0xffffffff), so READ CAPACITY(16) never gets sent. And if it was sent, the device wouldn't handle it anyway. > BTW Been looking at a USB-to-SATA adapter that uses the > UAS(P) transport. I thought nothing could have worse > SCSI compliance than USB mass storage devices. I was > wrong ... Well, a USB-to-SATA adapter _is_ a USB mass-storage device. What vendor and product? 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
