I think these are the alternatives.
-
scsiport bus filter driver: sits ontop of port FDO, attaches to port-
enumerated PDOs, translates verbs to french as appropriate. -
class lower filter: claims FDOs of interest preventing their claimage
by the class driver. (You might have to also generate new dev objects of
some other class, and as you say you might have to also be a lower filter
driver for that class, but I don’t really understand your requirements
here.)
I vote for #1. While bus filter drivers are undocumented, they are
definately supported as microsoft has at least one of them. This route
also is least invasive. Unless your other class is not even SCSI-
whatever, your filter driver just has to change the reported PDO hardware
ids from GENDISK to GENWHATEVER and you are done (at least you are done
in terms of getting the PDOs attached to the right stack.)
===========================
Mark Roddy
Consultant, Microsoft DDK MVP
Hollis Technology Solutions
xxxxx@hollistech.com
www.hollistech.com
603-321-1032
-----Original Message-----
From: “Phil Barila”
To: “NT Developers Interest List”
Date: Tue, 20 Aug 2002 16:09:41 -0600
Subject: [ntdev] Where to insert a filter to make a device of one class
look like another?
> I’m just starting into a project to make a SCSI disk appear to the
> system as
> if it is a different class of SCSI device. The type of device I am
> going to
> make it emulate has a Windows class driver for which the source is
> included
> in the DDK. Sorry, I’d love to tell you what I’m trying to emulate,
> but I
> can’t, yet. 
>
> My question is, where is the best place to intercept the IOs to
> translate
> them? The obvious place would be between the port and the class
> drivers,
> but that can have multiple meanings, I think. If attach as an upper
> filter
> for the Port driver, then I have to filter all of the SRBs into the
> Port,
> just to redirect the IOs to the single device I’m fiddling with, and
> that
> seems overly invasive. A (possible?) alternative is a lower filter to
> the
> both class drivers, which would redirect the single device to the other
> class driver. That seems more complex than the upper filter for the
> Port.
>
> Anything obvious I’ve overlooked? Suggestions? Comments? Think I’m
> nuts?
>
>
> Thanks,
>
> Phil
> –
> Philip D. Barila
> Seagate Technology, LLC
> (720) 684-1842
>
>
>
> —
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