Re: problem with new vforkdone stop reply in 7.10

[Don Breazeal <donb@codesourcery.com>]

On 9/15/2015 7:19 AM, Pedro Alves wrote:
> Hi Don,
> 
> Unfortunately, I missed in review that the vforkdone stop reply
> misses indicating the thread ID of the vfork parent which the
> event relates to:
> 
>  @cindex vfork events, remote reply
>  @item vfork
>  The packet indicates that @code{vfork} was called, and @var{r}
>  is the thread ID of the new child process. Refer to
>  @ref{thread-id syntax} for the format of the @var{thread-id}
>  field.  This packet is only applicable to targets that support
>  vfork events.
> 
>  @cindex vforkdone events, remote reply
>  @item vforkdone
>  The packet indicates that a child process created by a vfork
>  has either called @code{exec} or terminated, so that the
>  address spaces of the parent and child process are no longer
>  shared. The @var{r} part is ignored.  This packet is only
>  applicable to targets that support vforkdone events.
> 
> Unfortunately, this is not just a documentation issue.  GDBserver
> is really not specifying the thread ID.  I noticed because
> in non-stop mode, gdb complains:
> 
>  [Thread 6089.6089] #1 stopped.
>  #0  0x0000003615a011f0 in ?? ()
>  0x0000003615a011f0 in ?? ()
>  (gdb) set debug remote 1
>  (gdb) c
>  Continuing.
>  Sending packet: $QPassSignals:e;10;14;17;1a;1b;1c;21;24;25;2c;4c;#5f...Packet received: OK
>  Sending packet: $vCont;c:p17c9.17c9#88...Packet received: OK
>    Notification received: Stop:T05vfork:p17ce.17ce;06:40d7ffffff7f0000;07:30d7ffffff7f0000;10:e4c9eb1536000000;thread:p17c9.17c9;core:2;
>  Sending packet: $vStopped#55...Packet received: OK
>  Sending packet: $D;17ce#af...Packet received: OK
>  Sending packet: $vCont;c:p17c9.17c9#88...Packet received: OK
>    Notification received: Stop:T05vforkdone:;
>  No process or thread specified in stop reply: T05vforkdone:;
>  (gdb)
> 
> This is not non-stop-mode-specific, however.  Consider e.g., that
> in all-stop, you may be debugging more than one process at the
> same time.  You continue, and both processes vfork.  So if you next
> a T05vforkdone, how can we tell which of the parent processes
> has had its child exit/exec?
> 
> Thanks,
> Pedro Alves
> 
Hi Pedro,
Thanks for pointing this out.  I will take a look at it.  This case
would make an interesting test.
--Don