Date: Fri, 11 Dec 92 13:52:47 -0800
From: eichin AT ok DOT cygnus DOT com ("Mark W. Eichin")
To: mcastle AT mcs213k DOT cs DOT umr DOT edu
Cc: pef AT dcs DOT qmw DOT ac DOT uk, djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: re: gdb for DOS???

>> Hmm... thinking about the person from Cygnus who modified debug32 to work
>> over serial lines and use gdb on a unix box: did you have to modify gdb in
>> anyway?  And was there any success in running it on 2 pc's connected (both
>> running dos?)  Maybe support for one machine doing both under something like
>> desqview?
	I didn't have to modify gdb; it already has support for
"target remote /dev/ttya" for serial debugging when compiled as a
cross debugger (configure -target=go32 or something like that.) All I
did was modify debug.c somewhat, and embedded the i386stub.c (with
some DOSifications) in the driver. 
	I'd assume it could run between two PC's but haven't tried it.
It is possible to build a gdb hosted on go32 and targetting go32, and
use "target remote com1" or something to communicate, I just haven't
tried it (I only ever run DOS to do this development, I run linux most
of the time...) 
	An ambitious project would be to integrate the go32 extender
*into* gdb -- however, this would require building gdb as a DOS app
and it probably won't *fit* in 640K. Another possibility would be to
use the extender to provide multiple tasks, with seperate address
spaces, and then provide something at the level of the ptrace
interface to allow gdb to run in one task and the program under test
to run in another. This would require some amount of hacking in both
gdb and the extender, but perhaps not as much as it seems...
				_Mark_ <eichin AT athena DOT mit DOT edu>
				MIT Student Information Processing Board
				Cygnus Support <eichin AT cygnus DOT com>
ps. Someone suggested to me that it wouldn't be hard to provide
emulation of go32+dos under linux - it is already a 386-aout system,
it is just a matter of emulating the "int xxh" calls, if you ignore
the graphics handling (which is reasonable for text apps...) It
sounded interesting, but I haven't thought further on it.