Tagged Queueing and Dque Bit

[Daniel M. Eischen]

> > So I would suggest, that the driver should check also the Control Mode
> > Page (if available), and should honor the Dque bit (fall back to not use 
> > tagged queueing if Dque is set).
>
> This is exactly what the CAM layer does.  It may be the case that in Linux
> the individual control drivers have to do this, but it will be messy.  I
> don't think that the Linux aic7xxx driver has any code in it currently
> to queue and handle it's own SCSI commands.

Correct, though I am in the process of designing a BSD compat layer that
will queue and handle its own SCSI commands, while still using the 
Linux mid-level SCSI code to handle completion processing.  This will
allow the low-level driver to do BSD timeout()s and also make the
needed transport (xpt) calls from your new CAM code.  For instance,
the low-level driver will be able to freeze and release the device
queues.

I've been looking through your new CAM code and it is quite a
piece of work :-)

Dan Eischen
deischen at iworks.InterWorks.org