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Date: Mon, 05 May 2014 06:03:00 -0000
From: Eli Zaretskii <eliz@gnu.org>
Subject: Re: [PATCH v2 00/36] Guile extension language for GDB
In-reply-to: <f30b0b3709471cf98cf4c7a2454e9043@wh-stuttgart.net>
To: Tillmann Karras <tillmann@selfnet.de>
Cc: xdje42@gmail.com, gdb-patches@sourceware.org
Reply-to: Eli Zaretskii <eliz@gnu.org>
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References: <a3c401a4a9dd02c97721c4ef99a7e652@wh-stuttgart.net> <CAP9bCMTjnYu_d2H0SbpHp+TqvEBYxsyXZXi2Zj6iJLwTzrO58A@mail.gmail.com> <f30b0b3709471cf98cf4c7a2454e9043@wh-stuttgart.net>
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> Date: Sun, 04 May 2014 21:59:08 +0200
> From: Tillmann Karras <tillmann@selfnet.de>
> Cc: gdb-patches@sourceware.org
> 
> On 2014-04-28 00:15, Doug Evans wrote:
> > If you're running gdb under gdb, and the child gdb is hanging,
> > can you type Ctrl-C when it hangs, and then obtain a backtrace of the 
> > child gdb?
> 
> Pressing Ctrl-C just prints "[New Thread 0x7ffff4b6f700 (LWP 14601)]" 
> but I don't get any prompt.

My crystal ball says that Ctrl-C causes Guile to start its signal
delivery thread, which is the reason for the "New Thread" message you
see.

> > It's been suggested to give the following a try.
> > Does that fix things for you?
> > 
> > bash$ export GC_MARKERS=1
> > 
> > before starting gdb
> > It's a workaround for a libgc 7.4.0 bug.
> > I verified my arch-linux has libgc 7.4.0, but I may have just gotten 
> > lucky.
> 
> Yes, "gdb -ex 'set environment GC_MARKERS 1' -ex r gdb" makes it work 
> for me. (Maybe your test VM had only one core?)

What bug is that in libgc, and what are its symptoms?