Xref:	news2.mv.net comp.os.msdos.djgpp:614
From:	Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Issues with nearptr's.
Date:	Fri, 26 Jan 1996 18:16:15 CST
Organization:	Rice University, Houston, Texas
Lines:	16
Message-ID:	<31096ecf.sandmann@clio.rice.edu>
References:	<JTSILLA DOT 96Jan26100052 AT atlas DOT ccs DOT neu DOT edu>
Reply-To:	sandmann AT clio DOT rice DOT edu
NNTP-Posting-Host:	clio.rice.edu
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

> 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.

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