Re: [patch] gdbserver: qXfer multiprocess

[Aleksandar Ristovski <aristovski at qnx dot com>]

Pedro Alves wrote:
> On Wednesday 17 June 2009 18:19:10, Aleksandar Ristovski wrote:
>
> > Here is a patch that does what you described.
>
> Thanks.  This is still not complete, though.
>
> You need to make sure that the "multi_process" flag stays turned off
> if the backend doesn't support MP, otherwise, things like
> remote-utils.c:write_ptid will still misbehave (gdb will realize the
> target doesn't support multi-process, but the remote target will
> be replying with multi-process packets, how odd would that be?!).
> That flag is currently bound to GDB's multi-process support,
> because current gdbserver is assuming all backends support mp.
>
> 	    /* Record if GDB knows about multiprocess support.  */
> 	    if (strcmp (p, "multiprocess+") == 0)
> 	      multi_process = 1;
>
>
> To see this in action, you can connect with
> "target extended-remote :foo"/"set debug remote 1", and make sure that
> the packets flowing in both directions don't use multi-process thread
> id extensions (e.g., 'p1.1' vs '1').

Ok, then something like this?

--
Aleksandar Ristovski
QNX Software Systems


* target.h (supports_multiprocess): New function.
* server.c (handle_query): Use supports_multiprocess and output
multiprocess accordingly.
* linux-low.c (linux_supports_multiprocess): New function.
(linux_target_ops): Set supports_multiprocess.

Index: target.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/target.h,v
retrieving revision 1.36
diff -u -p -r1.36 target.h
--- target.h	1 Apr 2009 22:50:24 -0000	1.36
+++ target.h	17 Jun 2009 18:57:30 -0000
@@ -275,6 +283,8 @@ struct target_ops
   /* Switch to non-stop (1) or all-stop (0) mode.  Return 0 on
      success, -1 otherwise.  */
   int (*start_non_stop) (int);
+
+  int (*supports_multiprocess) (void);
 };
 
 extern struct target_ops *the_target;
@@ -311,6 +321,10 @@ void set_target_ops (struct target_ops *
 #define target_async(enable) \
   (the_target->async ? (*the_target->async) (enable) : 0)
 
+#define target_supports_multiprocess() \
+  (the_target->supports_multiprocess ? \
+   (*the_target->supports_multiprocess) () : 0)
+
 /* Start non-stop mode, returns 0 on success, -1 on failure.   */
 
 int start_non_stop (int nonstop);
Index: server.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/server.c,v
retrieving revision 1.97
diff -u -p -r1.97 server.c
--- server.c	24 May 2009 21:06:53 -0000	1.97
+++ server.c	17 Jun 2009 18:57:30 -0000
@@ -1106,7 +1106,11 @@ handle_query (char *own_buf, int packet_
       if (the_target->qxfer_osdata != NULL)
 	strcat (own_buf, ";qXfer:osdata:read+");
 
-      strcat (own_buf, ";multiprocess+");
+      if (target_supports_multiprocess ())
+	  strcat (own_buf, ";multiprocess+");
+      else
+	  /* Override GDB's ability to support multiprocess.  */
+	  multi_process = 0;
 
       if (target_supports_non_stop ())
 	strcat (own_buf, ";QNonStop+");
Index: linux-low.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/linux-low.c,v
retrieving revision 1.105
diff -u -p -r1.105 linux-low.c
--- linux-low.c	24 May 2009 17:44:19 -0000	1.105
+++ linux-low.c	17 Jun 2009 18:57:30 -0000
@@ -3008,6 +3008,12 @@ linux_start_non_stop (int nonstop)
   return 0;
 }
 
+static int
+linux_supports_multiprocess (void)
+{
+  return 1;
+}
+
 static struct target_ops linux_target_ops = {
   linux_create_inferior,
   linux_attach,
@@ -3045,6 +3053,7 @@ static struct target_ops linux_target_op
   linux_supports_non_stop,
   linux_async,
   linux_start_non_stop,
+  linux_supports_multiprocess
 };
 
 static void