Hi, I’m looking into the new CmRegisterCallbackEx routine and it requires a
parameter Altitude which says "A pointer to a UNICODE_STRING structure. This
structure must contain a string that represents the altitude of the calling
minifilter driver. "
Then the documentation talks about minifilter altitudes in a way which
suggests that this routine can only be called from a minifilter. The
question is, can this only be called from a minifilter or can normal drivers
also call this routine ?
If the answer is yes, then my next question is what objections are there
using the minifilter model for general purpose drivers which do not do
anything related to file systems. I personally like this model very much in
particular I like the way it communicates with user mode without having to
fool around with the service control manager.
Thanks,
/Daniel
“Daniel Terhell” wrote in message
news:xxxxx@ntfsd…
> Hi, I’m looking into the new CmRegisterCallbackEx routine and it requires
> a parameter Altitude which says "A pointer to a UNICODE_STRING structure.
> This structure must contain a string that represents the altitude of the
> calling minifilter driver. "
>
> Then the documentation talks about minifilter altitudes in a way which
> suggests that this routine can only be called from a minifilter. The
> question is, can this only be called from a minifilter or can normal
> drivers also call this routine ?
>
Interesting catch, I hadn’t looked at the CmRegisterCallbackEx, before your
post but I hope like heck it does not require a mini-filter. I’ve used
CmRegisterCallback a few of times, and none of them involved file system
filtering at all! Hopefully the goal here was to order the callbacks and
nothing more, or this is truly a case of Microsoft not understanding what
people do with the API.
–
Don Burn (MVP, Windows DDK)
Windows 2k/XP/2k3 Filesystem and Driver Consulting
http://www.windrvr.com
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Daniel
You have here no more than the new improved for vista registry callback
model borrowing concepts and lexicon from the file system mini-filter model.
Your driver that uses CmRegisterCallback[Ex] doesnt have to be a minifilter
but it can be a minifilter. I’d wonder a bit about a driver which is a
mini-filter but doesnt attach to volumes.
I assume you have not started to think about TxR so far 
Cheers
Lyndon
“Daniel Terhell” wrote in message
news:xxxxx@ntfsd…
> Hi, I’m looking into the new CmRegisterCallbackEx routine and it requires
> a parameter Altitude which says "A pointer to a UNICODE_STRING structure.
> This structure must contain a string that represents the altitude of the
> calling minifilter driver. "
>
> Then the documentation talks about minifilter altitudes in a way which
> suggests that this routine can only be called from a minifilter. The
> question is, can this only be called from a minifilter or can normal
> drivers also call this routine ?
>
> If the answer is yes, then my next question is what objections are there
> using the minifilter model for general purpose drivers which do not do
> anything related to file systems. I personally like this model very much
> in particular I like the way it communicates with user mode without having
> to fool around with the service control manager.
>
> Thanks,
>
> /Daniel
>
>