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

Doug Evans
2014-05-12T03:25:00Z

[+ ludovic]

On Sun, May 4, 2014 at 11:03 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>> 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?

A google search for libgc 7.4 GC_MARKERS found this: