MmMapViewInSystemSpace problem

NTFSD
1

Hi all,

I have been trying to use MmMapViewInSystemSpace but I have run into a
problem. As soon as I try to map more then 32 MB (of a 1 GB file) I get a
STATUS_NO_MEMORY error.

( ZwMapViewOfSection of the same section does not cause any problems).

Did anyone run into this issue and found a solution for it?

Best regards and thanks in advance.

Wim Vervoorn
Eltan Comm B.V.
The Netherlands

2

Address space is very limited in the kernel - most of it is already in use.
The OS is telling you that you are asking for too much. Instead of mapping
a 1GB file into the address space, you should maintain a window into it
(and, of course, this is probably one of the reasons this call is really
best used by the OS.)

For example, the cache manager maps its file components in using 256KB
windows. There is extra tracking required as a result, but this is what it
takes to work within a rather confined address space environment like the OS
kernel.

Regards,

Tony

Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com

Looking forward to seeing you at our revised and updated file systems class
in February 2003 (Boston, MA).

-----Original Message-----
From: Wim Vervoorn [mailto:xxxxx@eltan.com]
Sent: Friday, February 07, 2003 11:01 AM
To: File Systems Developers
Subject: [ntfsd] MmMapViewInSystemSpace problem

Hi all,

I have been trying to use MmMapViewInSystemSpace but I have run into a
problem. As soon as I try to map more then 32 MB (of a 1 GB file) I get a
STATUS_NO_MEMORY error.

( ZwMapViewOfSection of the same section does not cause any problems).

Did anyone run into this issue and found a solution for it?

Best regards and thanks in advance.

Wim Vervoorn
Eltan Comm B.V.
The Netherlands

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3

Hi Tony,

Thanks for the answer. I can understand what you are saying and it’s not a
problem to add some bookkeeping for this. The problem that remains is, how
do I specify an offset for the view? This call does not support it.

The only alternative I see at this moment is to use ZwMapViewOfSection and
lock down the pages that are required, create an MDL and get a system
address for that.

Is there a better alternative to that?

Thanks in advance,

Wim Vervoorn