Re: [PATCH v2 00/36] Guile extension language for GDB

Eli Zaretskii
2014-05-05T06:03:17Z

> 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?