Hi,
I am using a non cached read operation (by using self made Irp and setting
IRP_NO_CACHE flag on), To serve read requests from a file with an arbitrary
offset and length.
I found out that although the status retunred with success, the buffer is
not always correct!
The problem happens only when the offset is not aligned to 2.
I suspect that my problem is concerned with the file alignment.
What are the parameters constraints that should be considered when not
using a cached read operation?
Given the predefined byte offset and length, how can I optimize the
operation,
without performing memory allocation and memory copy?
Is this something you still have a question on? If so can you give some
more details about this, what exactly are you doing? Is this for your
own IRP that you are generating from inside your filter and are you
generating your own MDL?
I recently noticed that when you are generating your own MDL’s that you
MUST align the address and length to 2byte boundaries. This is because
most boards can not handle DMA’s to byte boundaries.
Neal Christiansen
-----Original Message-----
From: xxxxx@hotmail.com [mailto:xxxxx@hotmail.com]
Sent: Monday, August 21, 2000 6:00 PM
To: File Systems Developers
Subject: [ntfsd] File Alignment
Hi,
I am using a non cached read operation (by using self made Irp and
setting
IRP_NO_CACHE flag on), To serve read requests from a file with an
arbitrary
offset and length.
I found out that although the status retunred with success, the buffer
is
not always correct!
The problem happens only when the offset is not aligned to 2.
I suspect that my problem is concerned with the file alignment.
What are the parameters constraints that should be considered when not
using a cached read operation?
Given the predefined byte offset and length, how can I optimize the
operation,
without performing memory allocation and memory copy?
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