Re: Use of USB "Disk on a key" devices

Bruce M Simpson wrote:
> Kevin,
> 
> I purchased an 8Mb DiskOnKey device last week from PC World here in
> London for 10 GBP kast Thursday. I attempted to get the device to work
> simply byhacking its VID and PID into /src/sys/dev/usb/umass.c, but no joy.

Assuming it is similar to the two USB flash drives I've played with,
you need to hack /src/sys/cam/scsi/scsi_da.c to tell the scsi driver
about the capabilities of your device.

When you plug the device in to your system, it should be recognized.
with a log message something like

Aug 20 22:56:06 bobj /kernel: da0: <TREK2000 TD-G2 W1.1> Removable Direct Access SCSI-0 device

 From that I generated an entry in scsi_da.c that looks like this:

         {
                 /* Trek ThumbDrive Smart - another USB flash drive */
                 {T_DIRECT, SIP_MEDIA_REMOVABLE, "TREK2000", "TD-G2", "*"},
                 /*quirks*/ DA_Q_NO_6_BYTE|DA_Q_NO_SYNC_CACHE
         }

then I rebuilt and reinstalled my kernel and it worked.

You can use wildcards to allow one entry to cover a number of devices,
e.g. my first effort used the line

                {T_DIRECT, SIP_MEDIA_REMOVABLE, "TREK*", "*","*"},

which would work with just about any device from TREK. Now that I think about
it, I probably should be using

                {T_DIRECT, SIP_MEDIA_REMOVABLE, "TREK2000", "TD*","*"},

to pick up all models of the ThumbDrive, but that's a guess.

> 
> The device appears to be a BBB/SCSI-transparent one according to its
> configuration descriptor. After attempting to attach CAM, commands time out
> and are then refused - the device does not respond to SCSI_INQUIRY.

IIRC, my drive behaved similarly until I patched the driver.

The USB flash drives seem to universally implement an instruction set
that supports neither 6 byte commands nor cache sync. The "quirks"
entry tells the scsi driver not to use those commands. A device that
did not have any special quirks wouldn't need an entry in scsi_da.c

- Bob
> 
> There are a few further tips and tricks which I can perform, such as 6-byte
> command conversion within the SCSI stack. I will probably attempt to pin
> down further details of why the device isn't responding; I will be sure to
> let you know.
> 
> BMS
> 
> On Sun, Aug 11, 2002 at 04:50:53PM -0700, Kevin Oberman wrote:
> 
>>There are several vendors supplying solid-state USB "disk" drives of
>>between 8 MB and 512 MB. They claim to operate as USB disk drives and
>>require no drivers for Windows (newer than 98), Mac OS (9 and newer),
>>and Linux (with USB support). They come from several manufacturers
>>including TrekStor, Sandisk, EasyDisk, JMTek, Sony, SimpleTech, and
>>DiskOnKey (M-Systems).
>>
>>Has anyone used one of these devices and can they confirm whether or
>>not any particular brand works well? I've seen one report that one did
>>not work, but that's it.
> 
> 
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