problem with samsung flash

[Nate Lawson]

Ivan Frosty wrote:
> hello there, i have freebsd 6.1 pentiumII 355mhz processor and 128mb
> of ram. everytime i put my samsung 512mb in tha usb the machine doesnt
> boot it halts where the error be at if i pull it out it
> boots.........then if i put it back in i get an error.......whats with
> umass? i basically installed everybit and software of the unix i have
> so i dont know why i get the error anyhelp will be highly appreciated!
> 
> this is the error:
> 
> da0 at umass-sim0 bus0 target0wn0
> da0:<SAMSUNG flash Disk 1.06> Removable Direct Access SCSI-0 device
> da0:1.000MB/s transfers
> da0:511mb(1046720 512 byte sectors:64H 32s/T s11c)
> umass0:phase Error, residue = 0
> (da0:umass-sim0:0:0:0):synchronize cache failed, status == 0x4,scsi
> status == 0x0 opened disk da0->5!
> 
> thank you for your time

Hi, this is a common error and should be a FAQ somewhere.  Some USB 
devices can't handle SYNC CACHE, the command that says to write their 
data out to storage.  Most can or reject it with an error and continue. 
  Some hang, including yours.  You can add a SCSI quirk (no sync cache). 
  See the entries at the beginning of scsi_da.c for an example how to do 
it.  Your string would be "SAMSUNG", "flash Disk", "*".  See if that helps.

As far has fixing this problem permanently, does anyone have an idea on 
how the experimental work went with disabling sync cache if the INQ data 
indicates the device doesn't cache data (similar to Linux)?

Also, what do the scsi@ guys think of me adding a tunable/sysctl that is 
unit-specific so people can disable it without a quirk?  Example:
dev.da.0.no_sync_cache="1".  It would be off by default, of course.

-- 
Nate