Beginners's question on IRP_M?_FUNCTION

Hi,

I am unable to understand why the IRP_M?_FUNCTION codes are placed in
the stack locations. Does it ever happen that these codes are different
at different driver levels?

Thanks for any help in understanding…
Udas

yes it does happen. A disk driver, for example, converts IRP_MJ_READ
operations into IRP_MJ_SCSI operations which it sends to the driver for
the controller.

-p

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of udas2980
Sent: Wednesday, May 11, 2005 2:08 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] Beginners’s question on IRP_M?_FUNCTION

Hi,

I am unable to understand why the IRP_M?_FUNCTION codes are
placed in the stack locations. Does it ever happen that these
codes are different at different driver levels?

Thanks for any help in understanding…
Udas


Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as:
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The driver can reuse the same IRP for absolutely another operation while
sending it down the stack. For instance, it can receive MJ_WRITE, and send down
the MJ_SCSI IRP.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From: “udas2980”
Newsgroups: ntdev
To: “Windows System Software Devs Interest List”
Sent: Thursday, May 12, 2005 1:08 AM
Subject: [ntdev] Beginners’s question on IRP_M?_FUNCTION

> Hi,
>
> I am unable to understand why the IRP_M?_FUNCTION codes are placed in
> the stack locations. Does it ever happen that these codes are different
> at different driver levels?
>
> Thanks for any help in understanding…
> Udas
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com