You can also write your own class driver that loads very early and
simply claims all the devices so that no other class driver (disk, tape,
cd-rom, etc…) will be able to claim the devices. Then you provide your
own IOCTL interface to the class driver to perform the specific tasks
you need to perform on the devices; diagnostics, etc…
Jamey
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Daniel E. Germann
Sent: Tuesday, January 22, 2002 9:21 AM
To: NT Developers Interest List
Subject: [ntdev] RE: Windows 2000/XP SCSI filter driver
Many thanks to Gera, Mark, Max and Anton for their replies.
I guess I misunderstood the anecdote at the end of chapter 11 of the OSR
book (SCSI port driver read-only filter). It sounds like you can’t do
what they’re talking about in the Windows 2000/XP PnP world. (Are there
any plans to update the book for Windows 2000/XP and WDM? 
That
would be
GREAT!)
It looks like I am in for a lot of fun. Here’s the problem. I have a
laptop that will plug into the SCSI busses of target systems with
varying disk hardware for diagnostic and instrumentation purposes. I
must make 100% sure that the laptop accesses the hardware on the SCSI
bus in READ-ONLY mode. So, no filesystem mounting, no updating “dirty”
bits, etc. The laptop will inspect data on the target system and
display various statistics and reports. My idea was that if I inserted
a filter driver on top of the SCSI port driver, that all I/O requests on
the bus would get filtered (after all, I thought, wouldn’t disk.sys end
up sending IRPs to aic78xx.sys to do the disk I/O?). Evidently, I
completely misunderstood how all this works.
So, if I am understanding correctly now, I will have to add a lower
filter driver on disk.sys (to catch “normal” I/O) and keep my upper
filter driver on aic78xx.sys (to catch \Device\ScsiPortx I/O).
One more question: how do I ensure that *all* disks the laptop ever sees
(except, of course, my system disk) get filtered automatically? If I
install an .INF file for my filter driver that references hardware ID
“GenDisk”, I think it will work. But my concern is that the field
engineers using the diagnostic software on the laptops aren’t
necessarily the most technically aware users. If they see an Add New
Hardware dialog when they plug into a new target system, they’ll
probably get confused and tell it to install the standard disk driver –
and I’ll lose my read-only filter.
-Dan
Dan Germann
xxxxx@nospam.visi.com
-----Original Message-----
Subject: RE: Windows 2000/XP SCSI filter driver
From: “Roddy, Mark”
> Date: Mon, 21 Jan 2002 13:12:55 -0500
> X-Message-Number: 23
>
> Yeah, you are missing the fact that the scsiport driver is a bus
> driver, so the FDO you are filtering is the bus driver FDO, while data
> is (generally) targeted at the PDO’s managed by the bus driver, not
> the FDO. You either have to figure out how to implement the
> undocumented bus filter driver, or do the documented but ridiculous
> thing of being a lower filter driver for all of the possible FDO’s
> that can be configured on top of the scsi pdos.
>
> > -----Original Message-----
> > From: Daniel E. Germann [mailto:xxxxx@nospam.visi.com]
> > Sent: Monday, January 21, 2002 12:24 PM
> > To: NT Developers Interest List
> > Subject: [ntdev] Windows 2000/XP SCSI filter driver
> >
> >
> > I’m trying to build a Windows 2000/XP filter driver that filters all
> > traffic on a particular SCSI (or IDE) bus. I started with the
> > “toaster” filter driver sample, and added code to do a DebugPrint()
> > for every IRP the filter driver sees. I set the filter driver up as
> > an upper filter on top of aic78xx.sys (or atapi.sys) for the bus I
> > want to filter.
> >
> > The driver loads fine, and I think I am seeing all the PnP IRPs.
> > And if I open \Device\ScsiPort1 and talk to a device on that SCSI
> > bus, I can see all the IRPs I send to that device. But if I do a
> > disk read/write to a disk on that SCSI bus, I see nothing.
> >
> > Am I missing something? I did set the start type to
> > SERVICE_BOOT_START and the load order group to “SCSI miniport” (is
> > that still necessary with a PnP driver?). Has disk.sys already
> > hooked into aic78xx.sys by the time my filter driver loads? How do
> > I do this?
> >
> > Thank you!
> >
> > -Dan
> > –
> > Dan Germann
> > xxxxx@nospam.visi.com
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