What will happen if I call the Zw* calls in IRQLs other than the ones
prescribed. Will it result ina system crash or will the cal be masked off.
E.g. DDK says, “Callers of ZwWriteFile must be running at IRQL =
PASSIVE_LEVEL.” what will happen in this case?
A P wrote:
What will happen if I call the Zw* calls in IRQLs other than the ones
prescribed. Will it result ina system crash or will the cal be masked
off. E.g. DDK says, “Callers of ZwWriteFile must be running at IRQL =
PASSIVE_LEVEL.” what will happen in this case? — Questions? First
check the IFS FAQ at https://www.osronline.com/article.cfm?id=17 You are
currently subscribed to ntfsd as: unknown lmsubst tag argument: ‘’ To
unsubscribe send a blank email to xxxxx@lists.osr.com
BSOD most of the time.
When the system ask you to respect the IRQL it’s not for fun, it’s
simply because it needs to be at this IRQL to perform some operations
(most of the time : access paged pool).
–
Edouard.
I have always got BSODs.
Eduard, you say most of the time…can you point out a case where you dont
get a BSOD, I am curious.
> “Callers of ZwWriteFile must be running at IRQL = PASSIVE_LEVEL.”
what will happen in this case?
It depends on why exactly must a function run at certain IRQL level.
For example, if a function uses any paged memory (code or data)
it will crash in case that the memory will be paged out.
L.
The present and future behaviour of the operating system will become
undefined.
“A P” wrote in message news:xxxxx@ntfsd…
What will happen if I call the Zw* calls in IRQLs other than the ones
prescribed. Will it result ina system crash or will the cal be masked off.
E.g. DDK says, “Callers of ZwWriteFile must be running at IRQL =
PASSIVE_LEVEL.” what will happen in this case?
In case of the APC_LEVEL the system will hang, because it is impossible to execute an APC to complete an IRP, in case of the DISPATCH_LEVEL you will receive a BSOD, because it is impossible to execute Paging IO.
“A P” wrote in message news:xxxxx@ntfsd…
What will happen if I call the Zw* calls in IRQLs other than the ones prescribed. Will it result ina system crash or will the cal be masked off. E.g. DDK says, “Callers of ZwWriteFile must be running at IRQL = PASSIVE_LEVEL.” what will happen in this case?
yes, but the original poster was talking of “masking off” calls, I don’t
think that happens where teh call is masked off and the system driver
functions “perfectly otherwise ignoring this line” 
The results are unpredictable. Sometimes it might work, sometimes it
might crash, sometimes it might just cause a thread level hang. And
“sometimes” may depend upon the call, the thread, the time of day or the
state of the OS.
Break the rules at your own peril.
Regards,
Tony
Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
Looking forward to seeing you at the next OSR File Systems class in
Boston, MA April 18-21, 2006.
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of A P
Sent: Wednesday, March 22, 2006 12:57 AM
To: ntfsd redirect
Subject: [ntfsd] a ques
What will happen if I call the Zw* calls in IRQLs other than the ones
prescribed. Will it result ina system crash or will the cal be masked
off. E.g. DDK says, “Callers of ZwWriteFile must be running at IRQL =
PASSIVE_LEVEL.” what will happen in this case? — Questions? First
check the IFS FAQ at https://www.osronline.com/article.cfm?id=17 You are
currently subscribed to ntfsd as: unknown lmsubst tag argument: ‘’ To
unsubscribe send a blank email to xxxxx@lists.osr.com
Crash due to accessing paged stuff from >= DISPATCH or hang due to
unability to deliver the IO completion APC.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: “A P”
To: “Windows File Systems Devs Interest List”
Sent: Wednesday, March 22, 2006 9:56 AM
Subject: [ntfsd] a ques
What will happen if I call the Zw* calls in IRQLs other than the ones
prescribed. Will it result ina system crash or will the cal be masked off.
E.g. DDK says, “Callers of ZwWriteFile must be running at IRQL =
PASSIVE_LEVEL.” what will happen in this case?
—
Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17
You are currently subscribed to ntfsd as: unknown lmsubst tag argument: ‘’
To unsubscribe send a blank email to xxxxx@lists.osr.com