cvs commit: src/sys/cam/scsi scsi_da.c src/sys/dev/usb umass.c usbdevs

[Nate Lawson]

Florent Thoumie wrote:
> On Tuesday 31 January 2006 02:00, Nate Lawson wrote:
> 
>>Florent Thoumie wrote:
>>>It seems a lot of devices are concerned by the sync cache problem, would
>>>it be harmful to just remove this part of the code or could there be a
>>>way to detect if the device supports it or not?
>>
>>Well, it's important to run SYNC_CACHE in shutdown or possibly when
>>unmounting a filesystem.  Otherwise, data could be lost on boot.
>>However, I support adding a USB-specific mechanism that says SYNC_CACHE
>>should only be run on shutdown or device_eject, that way devices that
>>hang after this command is run would still work at runtime.  And SCSI
>>devices that support multiple calls to SYNC_CACHE (i.e. most non-USB
>>devs) would still work too.
>>
>>However, the first step is to investigate what windows and Linux do.
> 
> 
> Linux only sends the SYNCHRONIZE_CACHE command if the WCE (Write Cache Enable) 
> bit of the disk is set. I can't seem to find something equivalent to this in 
> our CAM framework. I have no particular SCSI knowledge but I guess I can have 
> a look at this tomorrow.
> 
> I'm forwarding this to freebsd-scsi@ (keep me CC'ed, as I'm not subscribed to 
> this list, yet).

Hmm, is WCE part of the inquiry response?  [moving to scsi@ list]

-- 
Nate