RE: DIRECT_IO IOCTL ,driver gets request as a BUFFERED_I- O ?

NTDEV
1

For both METHOD_IN_DIRECT and METHOD_OUT_DIRECT the Input buffer (to the
driver) is described by Irp.AssociatedIrp.SystemBuffer. The Output buffer is
described by Irp.MdlAddress. Your DeviceObject flags have no effect on the
construction of IOCTL Irps. If you received a NULL Irp.MdlAddress, then your
Output buffer parameter value and/or the OutputBufferSize parameter value
were NULL/zero. Note that for METHOD_*_DIRECT ‘OutputBuffer’ can transfer
data in either direction (from the driver or to the driver.)

-----Original Message-----
From: xxxxx@amd.com [mailto:xxxxx@amd.com]
Sent: Tuesday, February 19, 2002 9:08 PM
To: NT Developers Interest List
Subject: [ntdev] DIRECT_IO IOCTL ,driver gets request as a BUFFERED_IO ?

Hi,
I added a new METHOD_IN_DIRECT ioctl to a kernel mode driver.I changed
device object flags to pDeviceObject->Flags| = DO_DIRECT_IO.But when the
application send a buffer through this IOCTL call the buffer get as a
BUFFERED_IO call. That means pIrp->MdlAddress is NULL and I can see the
buffer at pIRP->AsscociatedIrp.SystemBuffer.Am I missing something?Any clue?

Thanks in advance,
Reeja

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