Re: RFC: Do not try g-packet-guess algorithm on exited targets

Daniel Jacobowitz
2008-11-24T14:49:13Z

On Sun, Nov 23, 2008 at 10:11:58PM +0000, Pedro Alves wrote:
> If we change the logic around to:
>
> /* Assume that the target is not running, unless we learn
> otherwise. */
> if (extended_p)
> target_mark_exited (target);
>
> Then would this in remote_read_description work instead of a
> new flag?

Like the attached? It works in my testing and is much nicer.

I did have a question while looking at this. We call
wait_for_inferior via start_remote when connecting to an all-stop
target, but not when connecting to a non-stop target. Does this
work because non-stop is always async, and we push the stop replies to
be noticed by the main event loop?

--
Daniel Jacobowitz
CodeSourcery

2008-11-23 Daniel Jacobowitz <dan@codesourcery.com>

PR gdb/2474
* remote.c (remote_read_description_p): New function.
(remote_start_remote): Try to fetch the target description
before adding shared libraries. Try again later if the
target is running but stopped.
(remote_open_1): Mark extended targets as exited by default.
(remote_read_description): Check target_has_execution.

Index: remote.c
===================================================================
RCS file: /cvs/src/src/gdb/remote.c,v
retrieving revision 1.329
diff -u -p -r1.329 remote.c
--- remote.c 19 Nov 2008 14:45:09 -0000 1.329
+++ remote.c 24 Nov 2008 14:40:47 -0000
@@ -234,6 +234,8 @@ static void remote_async_get_pending_eve

static void remote_terminal_ours (void);

+static int remote_read_description_p (struct target_ops *target);
+
/* The non-stop remote protocol provisions for one pending stop reply.
This is where we keep it until it is acknowledged. */

@@ -2549,15 +2551,15 @@ remote_start_remote (struct ui_out *uiou
getpkt (&rs->buf, &rs->buf_size, 0);
}

+ /* Next, if the target can specify a description, read it. We do
+ this before anything involving memory or registers. */
+ target_find_description ();
+
/* On OSs where the list of libraries is global to all
processes, we fetch them early. */
if (gdbarch_has_global_solist (target_gdbarch))
solib_add (NULL, args->from_tty, args->target, auto_solib_add);

- /* Next, if the target can specify a description, read it. We do
- this before anything involving memory or registers. */
- target_find_description ();
-
if (non_stop)
{
if (!rs->non_stop_aware)
@@ -2643,6 +2645,17 @@ remote_start_remote (struct ui_out *uiou

get_offsets (); /* Get text, data & bss offsets. */

+ /* If we could not find a description using qXfer, and we know
+ how to do it some other way, try again. This is not
+ supported for non-stop; it could be, but it is tricky if
+ there are no stopped threads when we connect. */
+ if (remote_read_description_p (args->target)
+ && gdbarch_target_desc (target_gdbarch) == NULL)
+ {
+ target_clear_description ();
+ target_find_description ();
+ }
+
/* Use the previously fetched status. */
gdb_assert (wait_status != NULL);
strcpy (rs->buf, wait_status);
@@ -3163,8 +3176,9 @@ remote_open_1 (char *name, int from_tty,
}
push_target (target); /* Switch to using remote target now. */

- /* Assume that the target is running, unless we learn otherwise. */
- target_mark_running (target);
+ /* Assume that the target is not running, until we learn otherwise. */
+ if (extended_p)
+ target_mark_exited (target);

/* Register extra event sources in the event loop. */
remote_async_inferior_event_token
@@ -7852,12 +7866,32 @@ register_remote_g_packet_guess (struct g
VEC_safe_push (remote_g_packet_guess_s, data->guesses, &new_guess);
}

+/* Return 1 if remote_read_description would do anything on this target
+ and architecture, 0 otherwise. */
+
+static int
+remote_read_description_p (struct target_ops *target)
+{
+ struct remote_g_packet_data *data
+ = gdbarch_data (target_gdbarch, remote_g_packet_data_handle);
+
+ if (!VEC_empty (remote_g_packet_guess_s, data->guesses))
+ return 1;
+
+ return 0;
+}
+
static const struct target_desc *
remote_read_description (struct target_ops *target)
{
struct remote_g_packet_data *data
= gdbarch_data (target_gdbarch, remote_g_packet_data_handle);

+ /* Do not try this during initial connection, when we do not know
+ whether there is a running but stopped thread. */
+ if (!target_has_execution || ptid_equal (inferior_ptid, null_ptid))
+ return NULL;
+
if (!VEC_empty (remote_g_packet_guess_s, data->guesses))
{
struct remote_g_packet_guess *guess;