Date: Mon, 5 Jul 1999 11:29:50 +0200 (MET DST) From: Nick Hibma <nick.hibma@jrc.it> To: Soren Schmidt <sos@freebsd.dk> Cc: Dag-Erling Smorgrav <des@flood.ping.uio.no>, green@FreeBSD.ORG, richard@cogsci.ed.ac.uk, phk@critter.freebsd.dk, freebsd-current@FreeBSD.ORG Subject: Re: IBM-DJNA drives on FreeBSD Message-ID: <Pine.GSO.3.95q.990705111928.676j-100000@elect8> In-Reply-To: <199907050843.KAA54290@freebsd.dk>
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> > I should have said "known bad configuration". I know Søren's ATA
> > driver supports UDMA on the Aladdin, but I don't have the luxury of
> > expendable file systems, so I don't use it. I also think it's the
> > wrong direction to go off in; if we're going to totally rewrite our
> > IDE driver, we should do it within the CAM framework.
>
> Do I hear a volounteer here ??
> What the new ATA/ATAPI driver is all about is mostly a rewrite of all
> the low level code, and that is still needed if you want to go the CAM way.
> The higher levels of the new ATA driver is simply a port of my allready
> done ATAPI drivers.
> There is nothing in the way of screwing a CAM interface ontop of that
> lowlevel code instead of/in parallel to the current highlvel code....
Yes yes yes! CAM on top of ATAPI. If we keep the command
creation/conversion layer in CAM and make CCB come out at the lower end,
we could instantly screw it on top of the USB Mass Storage driver (that
supports SCSI through CAM at the moment).
On a related edge:
Would it make sense to create a UFI command layer (USB floppies use it,
don't know what else) on top of CAM? Or am fundamentally wrong in
assuming that one can stack any command layer on top of CAM and abuse
it as a layer that provides common services, command queueing, error
handling?
It would like this:
SCSI UFI_da ATAPI
\ | /
CAM layer
|
USB Mass Storage Driver
/ | \
Bulk CB CBI
Cheers,
Nick
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