Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ttrdc!levy
From: levy@ttrdc.UUCP (Daniel R. Levy)
Newsgroups: comp.os.vms
Subject: Re: BACKUP under VMS 4.6 needs PHY_IO !?!?
Summary: what byte value(s) to use when restoring /traceback with PATCH?
Message-ID: <2093@ttrdc.UUCP>
Date: 17 Jan 88 02:05:47 GMT
References: <55rrk@byuvax.bitnet>
Organization: AT&T, Skokie, IL
Lines: 22

In article <55rrk@byuvax.bitnet>, rrk@byuvax.bitnet writes:
#> Five minutes with PATCH can make your /TRACEBACK image /NOTRACEBACK.  I
#> have done this numerous times to install images originally linked /TRACEBACK.
#> Use PATCH/ABSOLUTE so that you can access the image header.  The twelve
#> bytes, usually starting at byte 48 of the image header (30 hex for PATCH)
#> are transfer addresses.  A normal shareable image linked with /TRACEBACK
#> has one transfer address, as opposed to /NOTRACEBACK which has none.  Replace
#> this one (at byte 48) with a zero, and you have it.  There will still be
#> some extra debugger information at the end of the image file, but it will
#> be ignored.  You can also reverse the process to debug any system image
#> linked /NOTRACEBACK.

Ok, when "reversing the process" what value do you write into byte 48 (and
the following bytes)?  You could record this information somewhere for
an image that was originally /TRACEBACK and that you manually modified with
PATCH to be /NOTRACEBACK as described above, but what if it never was
/TRACEBACK???
-- 
|------------Dan Levy------------|  Path: ..!{akgua,homxb,ihnp4,ltuxa,mvuxa,
|         an Engihacker @        |  	<most AT&T machines>}!ttrdc!ttrda!levy
| AT&T Computer Systems Division |  Disclaimer?  Huh?  What disclaimer???
|--------Skokie, Illinois--------|