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Date: Sat, 09 Aug 2014 10:00:36 +0300
From: Eli Zaretskii <eliz AT gnu DOT org>
Subject: Re: gdb 7.8 no longer works with DJGPP.
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> Date: Sat, 09 Aug 2014 01:27:03 +0200
> From: Juan Manuel Guerrero <juan DOT guerrero AT gmx DOT de>
> 
> > Does GDB 7.7.1 work with DJGPP?
> Yes, both 2.03 and 2.04 port versions of GDB 7.7.1 work flawlessly
> with DJGPP.  I use them almost every day and I have never experienced
> any difficulties.

Then you have a starting point to search for changes that broke
DJGPP.

The only major feature added to 7.8 is the Guile support, which is
supposed to be orthogonal to DJGPP support, so I wouldn't think that's
the first suspect.  Rather, some infrastructure changes probably
caused that.  Since the immediate problem is with breakpoints, I'd
examine the breakpoint infrastructure changes first.

> (gdb) b main
> Breakpoint 1 at 0x1e04
                  ^^^^^^
Is this address correct?

> (gdb) r
> Starting program: h:/l/bins/bin/a.exe
> Warning:
> Cannot insert breakpoint 1.
> Cannot access memory at address 0x1e04

This means inserting a breakpoint at 0x1e04 returned EIO.  I suggest
to take a good look at the code that's involved in this.  I see that
in GDB-7.7.1, we had these 2 lines in go32-nat.c:

  go32_ops.to_insert_breakpoint = memory_insert_breakpoint;
  go32_ops.to_remove_breakpoint = memory_remove_breakpoint;

but these lines are no longer there, and instead the go32 target
inherits from inf_child_target.  Perhaps that's the cause of the
problem.

> I do not understand why the breakpoints are decremented (negative).

That's normal: these are internal breakpoints defined by GDB for its
internal purposes (like the 'finish' command).