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Mail Archives: djgpp/1996/01/29/08:43:06

Xref: news2.mv.net comp.os.msdos.djgpp:627
From: jan AT stack DOT urc DOT tue DOT nl (Jan Oonk)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Issues with nearptr's.
Date: 29 Jan 1996 10:59:28 +0100
Organization: MCGV Stack, Eindhoven University of Technology, the Netherlands.
Lines: 30
Message-ID: <4ei5q0$cdq@snail.stack.urc.tue.nl>
References: <JTSILLA DOT 96Jan26100052 AT atlas DOT ccs DOT neu DOT edu> <31096ecf DOT sandmann AT clio DOT rice DOT edu>
NNTP-Posting-Host: snail.stack.urc.tue.nl
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Charles Sandmann (sandmann AT clio DOT rice DOT edu) wrote:
: > I'd like to use nearptr's to access physical memory currently occupied
: > by video hardware. SOunds pretty simple, no? Well, I've read rumours
: > that there are dangers involved in setting the NEARPTR flag in my crt0 flags.

: The only known dangers are that a stray pointer can destroy the interrupt
: table, DOS, driver data, Windows, or anything else in memory.  If you always
: program without bugs, you have nothing to worry about :-)

: > One problem I have noticed is that when running under gdb, gdb
: > crashes when I use this flag and try to print out large data structures.
: > Are there any other possible issues? What's really going on in there?

: This really shouldn't be related, and I don't know why this would make
: a difference.  With nearptrs you could overwrite GDB's memory, but this
: might actually be seen with the default non-move sbrk anyway, since the
: debugger and program could end up with their memory laid out ABABAB.


I tried the nearptr example!

I got an compile-error:
crt0_flag_nonmove_sbrk not declared or something

it's not defined anywhere... i looked everywhere.. 
i am using djgpp v2 b4   gcc 2.7.1

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