Re: qXfer:exec-file:read and non multiprocess target

[Philippe Waroquiers <philippe dot waroquiers at skynet dot be>]

On Tue, 2015-05-05 at 12:02 +0100, Gary Benson wrote:
> The PID is fake because vgdb does not support multiprocess extensions.
> I don't like sending a fake/zero PID over the wire, but how about I
> change qXfer:exec-file:read to send a NULL annex if the remote does
> not have multiprocess extensions?  Can you make your side work with
> the patch inlined below?  If so I'll tidy and document it and submit
> it for review.
It looks effectively better to not send the fake or 0 pid
(e.g. similar to the qAttached packet).

The valgrind gdbserver side works ok with the patch to send an empty
annex.
This is the resulting exchange, traced at Valgrind side:
  ...
  --4980:3:  gdbsrv     getpkt ("qAttached");  [no ack] 
  --4980:3:  gdbsrv     putpkt ("$1#31"); [no ack]
  --4980:3:  gdbsrv     getpkt ("qXfer:exec-file:read::0,fff");  [no ack] 
  --4980:3:  gdbsrv     putpkt ("$l/home/philippe/valgrind/better_stats/memcheck/tests/trivialleak#2c"); [no ack]
  --4980:3:  gdbsrv     getpkt ("vFile:open:2f686f6d652f7068696c697070652f76616c6772696e642f6265747465725f73746174732f6d656d636865636b2f74657374732f7472697669616c6c65616b,0,0");  [no ack] 
  --4980:3:  gdbsrv     putpkt ("$#00"); [no ack]
  ...

and then GDB could properly use the returned exec-file
(even if vFile is not supported by Valgrind gdbserver).

Thanks

Philippe