Re: Why does this code crash with ACCVIO?

Article View: vmsnet.internals

Article #460

#460

From: Michael L. Hitch
Date: Sat, 12 Dec 1992 20:37

28 lines
1520 bytes

=>
=> >                                    I can manually deposit values at
=> > location pointed to by dest/r0 (using debugger 'deposit *dest=...'),
=> > so it is not a invalid address.
=>
=> But now for the interesting !
=>
=> The above test do NOT test what you think it tests at all !
=>
=> The debugger is capable of depositing values in NOWRT psects !
....
=> This little feature has been around for all the VMS versions I have
=> used and can be quite usefull.
=>
=> I once got the explanation that it is due to the fact, that the NOWRT
=> psect actually means user-mode:readonly and the debugger runs in
=> supervisor-mode !

   If the debugger couldn't write into user readonly data and code sections,
it would limit the utility of the debugger:  you wouldn't be able to modify
any readonly data or code while debugging a program.

---
Michael L. Hitch                        osymh@msu.oscs.montana.edu
Computer Consultant                     OSYMH@MTSUNIX1.BITNET
Office of Systems and Computing Services
Montana State University
Bozeman, MT     USA

Technical Details

Message-ID: <00964FAA.F91C1440.10804@trex.oscs.montana.edu>

Path: arc1-ca.pugleaf.net!sparky!uunet!think.com!sdd.hp.com!network.ucsd.edu!mvb.saic.com!macro32

Show Full Headers

Complete Article Headers

Path: arc1-ca.pugleaf.net!sparky!uunet!think.com!sdd.hp.com!network.ucsd.edu!mvb.saic.com!macro32
From: "Michael L. Hitch" <osymh%trex.oscs.montana.edu@MTSUNIX1.BITNET>
Newsgroups: vmsnet.internals
Subject: Re: Why does this code crash with ACCVIO?
Message-ID: <00964FAA.F91C1440.10804@trex.oscs.montana.edu>
Date: Sat, 12 Dec 1992 13:37:04 MST
Organization: Macro32<==>Vmsnet.Internals Gateway
X-Gateway-Source-Info: Mailing List
Lines: 28