From: Michael Snyder <msnyder@specifix.com>
To: Stephen Berman <Stephen.Berman@gmx.net>
Cc: gdb@sources.redhat.com
Subject: Re: GDB cannot access memory after Emacs abort
Date: Mon, 12 Nov 2007 05:24:00 -0000 [thread overview]
Message-ID: <1194844555.16917.319.camel@localhost.localdomain> (raw)
In-Reply-To: <87ir48gzet.fsf@escher.local.home>
On Mon, 2007-11-12 at 00:01 +0100, Stephen Berman wrote:
> On Sun, 11 Nov 2007 09:44:23 +0200 Eli Zaretskii <eliz@gnu.org> wrote:
>
> > the upshot of all this is that `bt' doesn't
> > work, as shown below:
> >
> >> > > (gdb) bt
> >> > > #0 abort () at emacs.c:431
> >> > > Cannot access memory at address 0xbfd6836c
> >> > > Cannot access memory at address 0x8321b6c
> >
> > Stack overflow, maybe?
>
> Due to an infinite loop in Emacs? (I don't know if the bug I reported
> caused this, maybe Jan D. can answer that.) But as I mentioned in my
> other followup, I've never experienced an infinite loop in Emacs that
> locked up X. If it was due to a stack overflow, does that mean GDB is
> above suspicion in this case?
No, it just means we don't yet have enough information to diagnose it.
Stack overflow could potentially produce a state that was too corrupt
for gdb to decypher, but we don't know yet if that's the case.
Now that I know that the target is x86-linux, I can reasonably
speculate that 0xbfd6836c looks like a stack address, and
0x8321b6c looks like a code or data address. But so far those
are only guesses, and it isn't yet clear why gdb would be unable
to access memory at those addresses.
I wonder -- after the above happens, what do you get if you
type the following at the (gdb) prompt:
x /i $eip
If you get the same error (Cannot access memory at ...),
then perhaps gdb has lost contact with the child process
entirely, and cannot access *any* memory.
If not, then some child memory is accessable and some is not
(which is not entirely surprising) -- and the question becomes,
why is gdb trying to read from memory that is not accessable?
next prev parent reply other threads:[~2007-11-12 5:24 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <87r6j6rvn3.fsf@escher.local.home>
2007-11-10 23:50 ` Stephen Berman
2007-11-11 6:46 ` Michael Snyder
2007-11-11 7:44 ` Eli Zaretskii
2007-11-11 23:05 ` Stephen Berman
2007-11-12 4:18 ` Eli Zaretskii
2007-11-12 5:24 ` Michael Snyder [this message]
2007-11-13 22:40 ` Stephen Berman
2007-11-13 23:20 ` Michael Snyder
2007-11-13 23:28 ` Dan Nicolaescu
2007-11-14 10:00 ` Stephen Berman
2007-11-13 23:57 ` Andreas Schwab
2007-11-11 19:22 ` Daniel Jacobowitz
2007-11-11 23:10 ` Stephen Berman
2007-11-12 0:39 ` Daniel Jacobowitz
2007-11-12 17:47 ` Jim Blandy
2007-11-12 19:44 ` Andreas Schwab
2007-11-13 22:36 ` Stephen Berman
2007-11-13 22:34 ` Stephen Berman
2007-11-13 23:14 ` Michael Snyder
2007-11-14 9:48 ` Stephen Berman
2007-11-13 23:51 ` Andreas Schwab
2007-11-12 7:39 ` Vladimir Prus
2007-11-13 22:36 ` Stephen Berman
2007-11-13 23:24 ` Michael Snyder
2007-11-14 9:50 ` Stephen Berman
2007-11-14 12:00 ` Michael Snyder
2007-11-14 19:24 ` Stephen Berman
2007-11-15 1:00 ` Michael Snyder
2007-11-11 23:01 ` Stephen Berman
2007-11-12 5:15 ` Michael Snyder
2007-11-14 9:55 ` Stephen Berman
2007-11-14 12:00 ` Michael Snyder
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