Re: [Qemu-devel] [PATCH] gdbstub: send a terminaison packet instead of crashing gdb

[KONRAD Frederic]

On 03/16/2018 05:34 PM, Peter Maydell wrote:
> On 16 March 2018 at 16:23, KONRAD Frederic <address@hidden> wrote:
> > Since the commit:
> > commit 4486e89c219c0d1b9bd8dfa0b1dd5b0d51ff2268
> > Author: Stefan Hajnoczi <address@hidden>
> > Date:   Wed Mar 7 14:42:05 2018 +0000
> >
> >      vl: introduce vm_shutdown()
> >
> > GDB crash when qemu exits (at least on sparc-softmmu):
> > Remote communication error.  Target disconnected.: Connection reset by peer.
> > Quitting: putpkt: write failed: Broken pipe.
> >
> > So send a packet to kill GDB before we exit QEMU:
> > [Inferior 1 (Thread 0) exited normally]
> >
> > Signed-off-by: KONRAD Frederic <address@hidden>
> > ---
> >   gdbstub.c              | 7 +++++++
> >   include/exec/gdbstub.h | 2 ++
> >   vl.c                   | 2 ++
> >   3 files changed, 11 insertions(+)
>
> We didn't send an exiting packet before commit 4486e89c219c0,
> so do you know why this worked before then? (Telling gdb we're
> exiting seems like the right thing, though.)

Hmmm good question, I didn't had time to investigate in detail

Before 4486e89c219c0:

(gdb) tar rem :1234
Remote debugging using :1234
0x40000000 in trap_table ()
(gdb) c
Continuing.
Remote connection closed

After 4486e89c219c0:

(gdb) tar rem :1234
Remote debugging using :1234
0x40000000 in trap_table ()
(gdb) c
Continuing.
putpkt: write failed: Connection reset by peer.

With the patch:

(gdb) tar rem :1234
Remote debugging using :1234
0x40000000 in trap_table ()
(gdb) c
Continuing.
[Inferior 1 (Thread 0) exited normally]

We use to have this patch in our repository to avoid the remote
connection closed above.

Thanks,
Fred

> thanks
> -- PMM