From - Wed Sep 24 14:57:00 1997
Path: news.mitre.org!blanket.mitre.org!agate!newsgate.duke.edu!nntprelay.mathworks.com!newsfeed.direct.ca!news.he.net!newshub.cts.com!newsfeed.cts.com!cmkrnl!jeh
From: jeh@cmkrnl.com (Jamie Hanrahan)
Newsgroups: comp.os.ms-windows.programmer.nt.kernel-mode
Subject: Re: ISR can't access User buffer HELP!!!!!
Message-ID: <1997Sep24.094915.8222@cmkrnl>
Date: 24 Sep 97 09:49:15 PST
References: <34283caf.349039037@news.connectnet.com>  <3429058A.C61F676C@vireo.com>
Organization: Kernel Mode Systems, San Diego, CA
Lines: 21

In article <3429058A.C61F676C@vireo.com>, Fred Hewett <hewett@vireo.com> writes:
> Jamie Hanrahan wrote:
> 
>> To get an address that is usable in arbitrary thread context, you must
>> call MmGetSystemAddressForMdl(Irp->MdlAddress).  You must do this in
>> the context of the requesting thread (ie in the dispatch routine that
>> handles the IRP).  
> 
> Please explain why it is necessary to be in the context of the requesting thread
> given that (1) there is a pointer to a struct _EPROCESS in the MDL, and (2) the
> DDK sample ATDISK calls this service from its StartIo routine.

Um, because I goofed!  You're right, it isn't necessary.  IRQL <= 
DISPATCH_LEVEL is all that's required.  Thanks!

	--- Jamie Hanrahan, Kernel Mode Systems, San Diego CA
        Internet: jeh@cmkrnl.com (JH645)  CompuServe: 74140,2055  
drivers, internals, networks, applications, and training for VMS and Windows NT
NT driver FAQ, links, and other information:  http://www.cmkrnl.com/

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