Sender:	rich AT phekda DOT freeserve DOT co DOT uk
Message-ID:	<394FE14A.776B1AA2@phekda.freeserve.co.uk>
Date:	Tue, 20 Jun 2000 22:25:30 +0100
From:	Richard Dawe <rich AT phekda DOT freeserve DOT co DOT uk>
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To:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
CC:	djgpp AT delorie DOT com
Subject:	Re: preprpcessor for overiding gcc optimation switch
References:	<Pine DOT LNX DOT 4 DOT 21 DOT 0006030531400 DOT 1081-100000 AT roadrunner DOT grendel DOT net> <83zop3o170 DOT fsf AT mercury DOT bitbucket> <25c58271 DOT fc969396 AT usw-ex0104-033 DOT remarq DOT com> <8ino7d$i9b$1 AT nets3 DOT rz DOT RWTH-Aachen DOT DE> <394F7467 DOT 6340126B AT phekda DOT freeserve DOT co DOT uk> <200006202008 DOT XAA23539 AT mailgw1 DOT netvision DOT net DOT il>
Reply-To:	djgpp AT delorie DOT com

Hello.

Eli Zaretskii wrote:
> I fail to see how calling a VxD can disable a breakpoint.  A
> breakpoint is a special instruction written to the program's code;
> unless Windows is smart enough to remove that special instruction and
> replace it with the original one, it can do nothing to interfere.

I didn't say that I understood why this was happening. I only observed
that gdb would not break when I used normal breakpoints; I could make it
break using hardware breakpoints. I have no idea if Windows is removing
the instructions. I have not tried to investigate this problem further,
since I was debugging libsocket at the time.

As a side issue, gdb crashes VMware (running Windows '95 or NT). If you
set a breakpoint, then gdb breaks and then you single-step (using s or n),
then VMware will crash. I reported this to the VMware folks and sent them
some code so they could reproduce this problem. They have not got back to
me. They said at the time that VMware was not really debugger-friendly
(i.e. debugging doesn't generally work under it), so I don't think this is
limited to gdb.

Bye,

-- 
Richard Dawe
[ mailto:richdawe AT bigfoot DOT com | http://www.bigfoot.com/~richdawe/ ]

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