[RFA] Unify async setting.

[RFA] Unify async setting.

[Vladimir Prus]

Presently, one need to use different commands to request async mode for linux
native and for async targets, which is hard on frontends.  Furthermore, the
relevant variables merely *allow* async mode, and there's no way for frontend
to make sure that async mode is actually in effect. This patch makes two things:

- Converts target-specific variables into a single 'set async' command.
- Adds new MI -list-target-features command that allows to check if current
target is in async mode.

The bulk of the patch is actually written by Pedro, I've only added MI/testsuite/doc
bits.

OK?

- Volodya

	* target.c (target_async_permitted, target_async_permitted_1)
	(set_maintenance_target_async_permitted)
	(show_maintenance_target_async_permitted): New.
	(initialize_targets): Register 'set target-async'.
	* target.h (target_async_permitted): Declare.
	* linux-nat.c (linux_nat_async_enabled)
	(linux_nat_async_permitted, set_maintenance_linux_async_permitted)
	(show_maintenance_linux_async_permitted): Remove.
	(sigchld_handler, linux_nat_is_async_p, linux_nat_can_async_p)
	(get_pending_events, linux_nat_async): Use target_async_permitted.
	(linux_nat_set_async_mode): Remove, moving the only used bits
	into...
	(linux_nat_setup_async): This.
	(_initialize_linux_nat): Do not register 'maint set linux-async'.
	Use linux_nat_setup_async.
	* remote.c (remote_async_permitted, remote_async_permitted_set)
	(set_maintenance_remote_async_permitted)
	(show_maintenance_remote_async_permitted): Remove.
	(remote_open_1, remote_terminal_inferior, remote_can_async_p)
	(remote_is_async_p): Use target_async_permitted.
	(_initialize_remote): Don't register 'main set remote-async'.
	* mi/mi-cmds.c (mi_cmds): Register -list-target-features.
	* mi/mi-cmds.h (mi_cmd_list_target_features): New.
	* mi/mi-main.c (mi_cmd_list_target_features): New.

	[testsuite/ChangeLog]
	* gdb.mi/mi-async.exp: Use 'set target-async'.
	* lib/mi-support.exp: Use 'set/show target-async'.

	[doc/ChangeLog]
	* gdb.texinfo (Background execution): Adjust example
	(GDB/MI Miscellaneous Commands): Document -list-target-features.
---
 gdb/doc/gdb.texinfo               |   33 +++++++++++--
 gdb/linux-nat.c                   |  101 +++++++-----------------------------
 gdb/mi/mi-cmds.c                  |    1 +
 gdb/mi/mi-cmds.h                  |    1 +
 gdb/mi/mi-main.c                  |   20 +++++++-
 gdb/remote.c                      |   54 +++-----------------
 gdb/target.c                      |   39 ++++++++++++++
 gdb/target.h                      |    4 ++
 gdb/testsuite/gdb.mi/mi-async.exp |    2 +-
 gdb/testsuite/lib/mi-support.exp  |    4 +-
 10 files changed, 124 insertions(+), 135 deletions(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 1ef4c8a..3ba9a59 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -4572,12 +4572,9 @@ independently and simultaneously.
 To enter non-stop mode, use this sequence of commands before you run
 or attach to your program:
 
-@c FIXME: can we fix this recipe to avoid the linux-async/remote-async details?
-
 @smallexample
 # Enable the async interface.  
-# For target remote, use remote-async instead of linux-async.
-maint set linux-async 1
+set async 1
 
 # If using the CLI, pagination breaks non-stop.
 set pagination off
@@ -22637,6 +22634,34 @@ option to the @code{-break-insert} command.
 
 @end itemize
 
+@subheading The @code{-list-target-features} Command
+@findex -list-target-features
+
+Returns a list of particular features that are supported by the
+target.  Those features affect the permitted MI commands, but 
+unlike the features reported by the @code{-list-features} command, the
+features depend on which target GDB is using at the moment.  Whenever
+a target can change, due to commands such as @code{-target-select},
+@code{-target-attach} or @code{-exec-run}, the list of target features
+may change, and the frontend should obtain it again.
+Example output:
+
+@smallexample
+(gdb) -list-features
+^done,result=["async"]
+@end smallexample
+
+The current list of features is:
+
+@itemize @minus
+@item
+@samp{async}---indicates that the target is capable of asynchronous
+command execution, which means that GDB will accept further commands
+even while the target is running.
+
+@end itemize
+
+
 @subheading The @code{-interpreter-exec} Command
 @findex -interpreter-exec
 
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index b59a35c..b25104e 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -276,9 +276,6 @@ static int linux_supports_tracevforkdone_flag = -1;
 
 /* Async mode support */
 
-/* True if async mode is currently on.  */
-static int linux_nat_async_enabled;
-
 /* Zero if the async mode, although enabled, is masked, which means
    linux_nat_wait should behave as if async mode was off.  */
 static int linux_nat_async_mask_value = 1;
@@ -3205,7 +3202,7 @@ linux_nat_pid_to_str (ptid_t ptid)
 static void
 sigchld_handler (int signo)
 {
-  if (linux_nat_async_enabled
+  if (target_async_permitted
       && linux_nat_async_events_state != sigchld_sync
       && signo == SIGCHLD)
     /* It is *always* a bug to hit this.  */
@@ -3992,45 +3989,15 @@ linux_trad_target (CORE_ADDR (*register_u_offset)(struct gdbarch *, int, int))
   return t;
 }
 
-/* Controls if async mode is permitted.  */
-static int linux_async_permitted = 0;
-
-/* The set command writes to this variable.  If the inferior is
-   executing, linux_nat_async_permitted is *not* updated.  */
-static int linux_async_permitted_1 = 0;
-
-static void
-set_maintenance_linux_async_permitted (char *args, int from_tty,
-			       struct cmd_list_element *c)
-{
-  if (target_has_execution)
-    {
-      linux_async_permitted_1 = linux_async_permitted;
-      error (_("Cannot change this setting while the inferior is running."));
-    }
-
-  linux_async_permitted = linux_async_permitted_1;
-  linux_nat_set_async_mode (linux_async_permitted);
-}
-
-static void
-show_maintenance_linux_async_permitted (struct ui_file *file, int from_tty,
-			    struct cmd_list_element *c, const char *value)
-{
-  fprintf_filtered (file, _("\
-Controlling the GNU/Linux inferior in asynchronous mode is %s.\n"),
-		    value);
-}
-
 /* target_is_async_p implementation.  */
 
 static int
 linux_nat_is_async_p (void)
 {
   /* NOTE: palves 2008-03-21: We're only async when the user requests
-     it explicitly with the "maintenance set linux-async" command.
+     it explicitly with the "maintenance set target-async" command.
      Someday, linux will always be async.  */
-  if (!linux_async_permitted)
+  if (!target_async_permitted)
     return 0;
 
   return 1;
@@ -4042,9 +4009,9 @@ static int
 linux_nat_can_async_p (void)
 {
   /* NOTE: palves 2008-03-21: We're only async when the user requests
-     it explicitly with the "maintenance set linux-async" command.
+     it explicitly with the "maintenance set target-async" command.
      Someday, linux will always be async.  */
-  if (!linux_async_permitted)
+  if (!target_async_permitted)
     return 0;
 
   /* See target.h/target_async_mask.  */
@@ -4125,7 +4092,7 @@ get_pending_events (void)
 {
   int status, options, pid;
 
-  if (!linux_nat_async_enabled
+  if (!target_async_permitted
       || linux_nat_async_events_state != sigchld_async)
     internal_error (__FILE__, __LINE__,
 		    "get_pending_events called with async masked");
@@ -4329,7 +4296,7 @@ static void
 linux_nat_async (void (*callback) (enum inferior_event_type event_type,
 				   void *context), void *context)
 {
-  if (linux_nat_async_mask_value == 0 || !linux_nat_async_enabled)
+  if (linux_nat_async_mask_value == 0 || !target_async_permitted)
     internal_error (__FILE__, __LINE__,
 		    "Calling target_async when async is masked");
 
@@ -4353,35 +4320,6 @@ linux_nat_async (void (*callback) (enum inferior_event_type event_type,
   return;
 }
 
-/* Enable/Disable async mode.  */
-
-static void
-linux_nat_set_async_mode (int on)
-{
-  if (linux_nat_async_enabled != on)
-    {
-      if (on)
-	{
-	  gdb_assert (waitpid_queue == NULL);
-	  if (pipe (linux_nat_event_pipe) == -1)
-	    internal_error (__FILE__, __LINE__,
-			    "creating event pipe failed.");
-	  fcntl (linux_nat_event_pipe[0], F_SETFL, O_NONBLOCK);
-	  fcntl (linux_nat_event_pipe[1], F_SETFL, O_NONBLOCK);
-	}
-      else
-	{
-	  drain_queued_events (-1);
-	  linux_nat_num_queued_events = 0;
-	  close (linux_nat_event_pipe[0]);
-	  close (linux_nat_event_pipe[1]);
-	  linux_nat_event_pipe[0] = linux_nat_event_pipe[1] = -1;
-
-	}
-    }
-  linux_nat_async_enabled = on;
-}
-
 static int
 send_sigint_callback (struct lwp_info *lp, void *data)
 {
@@ -4478,6 +4416,18 @@ linux_nat_get_siginfo (ptid_t ptid)
   return &lp->siginfo;
 }
 
+/* Enable/Disable async mode.  */
+
+static void
+linux_nat_setup_async (void)
+{
+  if (pipe (linux_nat_event_pipe) == -1)
+    internal_error (__FILE__, __LINE__,
+		    "creating event pipe failed.");
+  fcntl (linux_nat_event_pipe[0], F_SETFL, O_NONBLOCK);
+  fcntl (linux_nat_event_pipe[1], F_SETFL, O_NONBLOCK);
+}
+
 void
 _initialize_linux_nat (void)
 {
@@ -4510,16 +4460,6 @@ Enables printf debugging output."),
 			    show_debug_linux_nat_async,
 			    &setdebuglist, &showdebuglist);
 
-  add_setshow_boolean_cmd ("linux-async", class_maintenance,
-			   &linux_async_permitted_1, _("\
-Set whether gdb controls the GNU/Linux inferior in asynchronous mode."), _("\
-Show whether gdb controls the GNU/Linux inferior in asynchronous mode."), _("\
-Tells gdb whether to control the GNU/Linux inferior in asynchronous mode."),
-			   set_maintenance_linux_async_permitted,
-			   show_maintenance_linux_async_permitted,
-			   &maintenance_set_cmdlist,
-			   &maintenance_show_cmdlist);
-
   /* Get the default SIGCHLD action.  Used while forking an inferior
      (see linux_nat_create_inferior/linux_nat_async_events).  */
   sigaction (SIGCHLD, NULL, &sigchld_default_action);
@@ -4551,8 +4491,7 @@ Tells gdb whether to control the GNU/Linux inferior in asynchronous mode."),
   sigemptyset (&async_sigchld_action.sa_mask);
   async_sigchld_action.sa_flags = SA_RESTART;
 
-  /* Install the default mode.  */
-  linux_nat_set_async_mode (linux_async_permitted);
+  linux_nat_setup_async ();
 
   add_setshow_boolean_cmd ("disable-randomization", class_support,
 			   &disable_randomization, _("\
diff --git a/gdb/mi/mi-cmds.c b/gdb/mi/mi-cmds.c
index 3ae4c95..ca0f428 100644
--- a/gdb/mi/mi-cmds.c
+++ b/gdb/mi/mi-cmds.c
@@ -89,6 +89,7 @@ struct mi_cmd mi_cmds[] =
   { "inferior-tty-show", { NULL, 0 }, mi_cmd_inferior_tty_show},
   { "interpreter-exec", { NULL, 0 }, mi_cmd_interpreter_exec},
   { "list-features", { NULL, 0 }, mi_cmd_list_features},
+  { "list-target-features", { NULL, 0 }, mi_cmd_list_target_features},
   { "overlay-auto", { NULL, 0 }, NULL },
   { "overlay-list-mapping-state", { NULL, 0 }, NULL },
   { "overlay-list-overlays", { NULL, 0 }, NULL },
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index 72e18c7..16887ae 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -66,6 +66,7 @@ extern mi_cmd_argv_ftype mi_cmd_inferior_tty_set;
 extern mi_cmd_argv_ftype mi_cmd_inferior_tty_show;
 extern mi_cmd_argv_ftype mi_cmd_interpreter_exec;
 extern mi_cmd_argv_ftype mi_cmd_list_features;
+extern mi_cmd_argv_ftype mi_cmd_list_target_features;
 extern mi_cmd_argv_ftype mi_cmd_stack_info_depth;
 extern mi_cmd_argv_ftype mi_cmd_stack_info_frame;
 extern mi_cmd_argv_ftype mi_cmd_stack_list_args;
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index 733fc47..b18326d 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -915,7 +915,25 @@ mi_cmd_list_features (char *command, char **argv, int argc)
 
   error ("-list-features should be passed no arguments");
 }
- 
+
+void
+mi_cmd_list_target_features (char *command, char **argv, int argc)
+{
+  if (argc == 0)
+    {
+      struct cleanup *cleanup = NULL;
+      cleanup = make_cleanup_ui_out_list_begin_end (uiout, "features");      
+
+      if (target_can_async_p ())
+	ui_out_field_string (uiout, NULL, "async");
+      
+      do_cleanups (cleanup);
+      return;
+    }
+
+  error ("-list-target-features should be passed no arguments");
+}
+
 /* Execute a command within a safe environment.
    Return <0 for error; >=0 for ok.
 
diff --git a/gdb/remote.c b/gdb/remote.c
index 2782d05..af3b0b8 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -209,33 +209,6 @@ static void show_remote_protocol_packet_cmd (struct ui_file *file,
 
 void _initialize_remote (void);
 
-/* Controls if async mode is permitted.  */
-static int remote_async_permitted = 0;
-
-static int remote_async_permitted_set = 0;
-
-static void
-set_maintenance_remote_async_permitted (char *args, int from_tty,
-					struct cmd_list_element *c)
-{
-  if (target_has_execution)
-    {
-      remote_async_permitted_set = remote_async_permitted; /* revert */
-      error (_("Cannot change this setting while the inferior is running."));
-    }
-
-  remote_async_permitted = remote_async_permitted_set;
-}
-
-static void
-show_maintenance_remote_async_permitted (struct ui_file *file, int from_tty,
-					 struct cmd_list_element *c, const char *value)
-{
-  fprintf_filtered (file, _("\
-Controlling the remote inferior in asynchronous mode is %s.\n"),
-		    value);
-}
-
 /* For "remote".  */
 
 static struct cmd_list_element *remote_cmdlist;
@@ -2703,7 +2676,7 @@ remote_open_1 (char *name, int from_tty, struct target_ops *target, int extended
 	   "(e.g. /dev/ttyS0, /dev/ttya, COM1, etc.)."));
 
   /* See FIXME above.  */
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     wait_forever_enabled_p = 1;
 
   /* If we're connected to a running target, target_preopen will kill it.
@@ -2824,7 +2797,7 @@ remote_open_1 (char *name, int from_tty, struct target_ops *target, int extended
      this before anything involving memory or registers.  */
   target_find_description ();
 
-  if (remote_async_permitted)
+  if (target_async_permitted)
     {
       /* With this target we start out by owning the terminal.  */
       remote_async_terminal_ours_p = 1;
@@ -2869,13 +2842,13 @@ remote_open_1 (char *name, int from_tty, struct target_ops *target, int extended
     if (ex.reason < 0)
       {
 	pop_target ();
-	if (remote_async_permitted)
+	if (target_async_permitted)
 	  wait_forever_enabled_p = 1;
 	throw_exception (ex);
       }
   }
 
-  if (remote_async_permitted)
+  if (target_async_permitted)
     wait_forever_enabled_p = 1;
 
   if (extended_p)
@@ -3403,7 +3376,7 @@ Give up (and stop debugging it)? "))
 static void
 remote_terminal_inferior (void)
 {
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     /* Nothing to do.  */
     return;
 
@@ -3433,7 +3406,7 @@ remote_terminal_inferior (void)
 static void
 remote_terminal_ours (void)
 {
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     /* Nothing to do.  */
     return;
 
@@ -7265,7 +7238,7 @@ Specify the serial device it is connected to (e.g. /dev/ttya).";
 static int
 remote_can_async_p (void)
 {
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     /* We only enable async when the user specifically asks for it.  */
     return 0;
 
@@ -7276,7 +7249,7 @@ remote_can_async_p (void)
 static int
 remote_is_async_p (void)
 {
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     /* We only enable async when the user specifically asks for it.  */
     return 0;
 
@@ -7630,17 +7603,6 @@ Set the remote pathname for \"run\""), _("\
 Show the remote pathname for \"run\""), NULL, NULL, NULL,
 				   &remote_set_cmdlist, &remote_show_cmdlist);
 
-  add_setshow_boolean_cmd ("remote-async", class_maintenance,
-			   &remote_async_permitted_set, _("\
-Set whether gdb controls the remote inferior in asynchronous mode."), _("\
-Show whether gdb controls the remote inferior in asynchronous mode."), _("\
-Tells gdb whether to control the remote inferior in asynchronous mode."),
-			   set_maintenance_remote_async_permitted,
-			   show_maintenance_remote_async_permitted,
-			   &maintenance_set_cmdlist,
-			   &maintenance_show_cmdlist);
-
-
   /* Eventually initialize fileio.  See fileio.c */
   initialize_remote_fileio (remote_set_cmdlist, remote_show_cmdlist);
 
diff --git a/gdb/target.c b/gdb/target.c
index 6cda095..0dbe49b 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -3136,6 +3136,35 @@ maintenance_print_target_stack (char *cmd, int from_tty)
     }
 }
 
+/* Controls if async mode is permitted.  */
+int target_async_permitted = 0;
+
+/* The set command writes to this variable.  If the inferior is
+   executing, linux_nat_async_permitted is *not* updated.  */
+static int target_async_permitted_1 = 0;
+
+static void
+set_maintenance_target_async_permitted (char *args, int from_tty,
+					struct cmd_list_element *c)
+{
+  if (target_has_execution)
+    {
+      target_async_permitted_1 = target_async_permitted;
+      error (_("Cannot change this setting while the inferior is running."));
+    }
+
+  target_async_permitted = target_async_permitted_1;
+}
+
+static void
+show_maintenance_target_async_permitted (struct ui_file *file, int from_tty,
+					 struct cmd_list_element *c,
+					 const char *value)
+{
+  fprintf_filtered (file, _("\
+Controlling the inferior in asynchronous mode is %s.\n"), value);
+}
+
 void
 initialize_targets (void)
 {
@@ -3173,5 +3202,15 @@ result in significant performance improvement for remote targets."),
            _("Print the name of each layer of the internal target stack."),
            &maintenanceprintlist);
 
+  add_setshow_boolean_cmd ("target-async", no_class,
+			   &target_async_permitted_1, _("\
+Set whether gdb controls the inferior in asynchronous mode."), _("\
+Show whether gdb controls the inferior in asynchronous mode."), _("\
+Tells gdb whether to control the inferior in asynchronous mode."),
+			   set_maintenance_target_async_permitted,
+			   show_maintenance_target_async_permitted,
+			   &setlist,
+			   &showlist);
+
   target_dcache = dcache_init ();
 }
diff --git a/gdb/target.h b/gdb/target.h
index e242566..3a1d4b7 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -956,6 +956,10 @@ int target_follow_fork (int follow_child);
 #define target_can_lock_scheduler \
      (current_target.to_has_thread_control & tc_schedlock)
 
+/* Should the target enable async mode if it is supported?  Temporary
+   cludge until async mode is a strict superset of sync mode.  */
+extern int target_async_permitted;
+
 /* Can the target support asynchronous execution? */
 #define target_can_async_p() (current_target.to_can_async_p ())
 
diff --git a/gdb/testsuite/gdb.mi/mi-async.exp b/gdb/testsuite/gdb.mi/mi-async.exp
index 9ac91fd..a251c32 100644
--- a/gdb/testsuite/gdb.mi/mi-async.exp
+++ b/gdb/testsuite/gdb.mi/mi-async.exp
@@ -27,7 +27,7 @@ if { !([isnative] && [istarget *-linux*]) \
 
 # The plan is for async mode to become the default but toggle for now.
 set saved_gdbflags $GDBFLAGS
-set GDBFLAGS [concat $GDBFLAGS " -ex \"maint set linux-async on\""]
+set GDBFLAGS [concat $GDBFLAGS " -ex \"set target-async on\""]
 
 load_lib mi-support.exp
 
diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index 762e4e2..09d3eeb 100644
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -912,10 +912,10 @@ proc detect_async {} {
     global async
     global mi_gdb_prompt
 
-    send_gdb "maint show linux-async\n"
+    send_gdb "show target-async\n"
         
     gdb_expect {
-        -re ".*Controlling the GNU/Linux inferior in asynchronous mode is on...*$mi_gdb_prompt$" {
+        -re ".*Controlling the inferior in asynchronous mode is on...*$mi_gdb_prompt$" {
             set async 1
         }
         -re ".*$mi_gdb_prompt$" {
-- 
1.5.3.5

Re: [RFA] Unify async setting.

[Eli Zaretskii]

> From: Vladimir Prus <vladimir@codesourcery.com>
> Date: Fri, 15 Aug 2008 21:07:19 +0400
> 
> 	[doc/ChangeLog]
> 	* gdb.texinfo (Background execution): Adjust example
> 	(GDB/MI Miscellaneous Commands): Document -list-target-features.

This part is okay, except that...

> +@itemize @minus
> +@item
> +@samp{async}---indicates that the target is capable of asynchronous
> +command execution, which means that GDB will accept further commands
> +even while the target is running.
> +
> +@end itemize

You want "@table @samp" here, not @itemize.  Like this:

  @table @samp
  @item async
  Indicates that the target is capable of asynchronous command
  execution, which means that GDB will accept further commands
  while the debuggee is running.

@itemize is for ordered lists, like when you want to show several
alternatives or a sequence of actions.  When you want to describe
several attributes, you need to distinguish between the attribute and
its description, which is what @table is for.

(Note that I removed the "even" part.)  And please use @value{GDBN}
instead of a literal "GDB".

RE: [RFA] Unify async setting.

[Marc Khouzam]

Hi,

it think it is great to have a single command to set async for native
or targets.
Will the command be 'set async' or 'set target-async', the patch
seems to use target-async.

Thanks

> -----Original Message-----
> From: gdb-patches-owner@sourceware.org
> [mailto:gdb-patches-owner@sourceware.org]On Behalf Of Vladimir Prus
> Sent: Friday, August 15, 2008 1:07 PM
> To: gdb-patches@sources.redhat.com
> Subject: [RFA] Unify async setting.
> 
> 
> 
> Presently, one need to use different commands to request 
> async mode for linux
> native and for async targets, which is hard on frontends.  
> Furthermore, the
> relevant variables merely *allow* async mode, and there's no 
> way for frontend
> to make sure that async mode is actually in effect. This 
> patch makes two things:
> 
> - Converts target-specific variables into a single 'set 
> async' command.
> - Adds new MI -list-target-features command that allows to 
> check if current
> target is in async mode.
> 
> The bulk of the patch is actually written by Pedro, I've only 
> added MI/testsuite/doc
> bits.
> 
> OK?
> 
> - Volodya
> 
> 	* target.c (target_async_permitted, target_async_permitted_1)
> 	(set_maintenance_target_async_permitted)
> 	(show_maintenance_target_async_permitted): New.
> 	(initialize_targets): Register 'set target-async'.
> 	* target.h (target_async_permitted): Declare.
> 	* linux-nat.c (linux_nat_async_enabled)
> 	(linux_nat_async_permitted, 
> set_maintenance_linux_async_permitted)
> 	(show_maintenance_linux_async_permitted): Remove.
> 	(sigchld_handler, linux_nat_is_async_p, linux_nat_can_async_p)
> 	(get_pending_events, linux_nat_async): Use 
> target_async_permitted.
> 	(linux_nat_set_async_mode): Remove, moving the only used bits
> 	into...
> 	(linux_nat_setup_async): This.
> 	(_initialize_linux_nat): Do not register 'maint set 
> linux-async'.
> 	Use linux_nat_setup_async.
> 	* remote.c (remote_async_permitted, remote_async_permitted_set)
> 	(set_maintenance_remote_async_permitted)
> 	(show_maintenance_remote_async_permitted): Remove.
> 	(remote_open_1, remote_terminal_inferior, remote_can_async_p)
> 	(remote_is_async_p): Use target_async_permitted.
> 	(_initialize_remote): Don't register 'main set remote-async'.
> 	* mi/mi-cmds.c (mi_cmds): Register -list-target-features.
> 	* mi/mi-cmds.h (mi_cmd_list_target_features): New.
> 	* mi/mi-main.c (mi_cmd_list_target_features): New.
> 
> 	[testsuite/ChangeLog]
> 	* gdb.mi/mi-async.exp: Use 'set target-async'.
> 	* lib/mi-support.exp: Use 'set/show target-async'.
> 
> 	[doc/ChangeLog]
> 	* gdb.texinfo (Background execution): Adjust example
> 	(GDB/MI Miscellaneous Commands): Document -list-target-features.
> ---
>  gdb/doc/gdb.texinfo               |   33 +++++++++++--
>  gdb/linux-nat.c                   |  101 
> +++++++-----------------------------
>  gdb/mi/mi-cmds.c                  |    1 +
>  gdb/mi/mi-cmds.h                  |    1 +
>  gdb/mi/mi-main.c                  |   20 +++++++-
>  gdb/remote.c                      |   54 +++-----------------
>  gdb/target.c                      |   39 ++++++++++++++
>  gdb/target.h                      |    4 ++
>  gdb/testsuite/gdb.mi/mi-async.exp |    2 +-
>  gdb/testsuite/lib/mi-support.exp  |    4 +-
>  10 files changed, 124 insertions(+), 135 deletions(-)
> 
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 1ef4c8a..3ba9a59 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -4572,12 +4572,9 @@ independently and simultaneously.
>  To enter non-stop mode, use this sequence of commands before you run
>  or attach to your program:
>  
> -@c FIXME: can we fix this recipe to avoid the 
> linux-async/remote-async details?
> -
>  @smallexample
>  # Enable the async interface.  
> -# For target remote, use remote-async instead of linux-async.
> -maint set linux-async 1
> +set async 1
>  
>  # If using the CLI, pagination breaks non-stop.
>  set pagination off
> @@ -22637,6 +22634,34 @@ option to the @code{-break-insert} command.
>  
>  @end itemize
>  
> +@subheading The @code{-list-target-features} Command
> +@findex -list-target-features
> +
> +Returns a list of particular features that are supported by the
> +target.  Those features affect the permitted MI commands, but 
> +unlike the features reported by the @code{-list-features} 
> command, the
> +features depend on which target GDB is using at the moment.  Whenever
> +a target can change, due to commands such as @code{-target-select},
> +@code{-target-attach} or @code{-exec-run}, the list of 
> target features
> +may change, and the frontend should obtain it again.
> +Example output:
> +
> +@smallexample
> +(gdb) -list-features
> +^done,result=["async"]
> +@end smallexample
> +
> +The current list of features is:
> +
> +@itemize @minus
> +@item
> +@samp{async}---indicates that the target is capable of asynchronous
> +command execution, which means that GDB will accept further commands
> +even while the target is running.
> +
> +@end itemize
> +
> +
>  @subheading The @code{-interpreter-exec} Command
>  @findex -interpreter-exec
>  
> diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
> index b59a35c..b25104e 100644
> --- a/gdb/linux-nat.c
> +++ b/gdb/linux-nat.c
> @@ -276,9 +276,6 @@ static int 
> linux_supports_tracevforkdone_flag = -1;
>  
>  /* Async mode support */
>  
> -/* True if async mode is currently on.  */
> -static int linux_nat_async_enabled;
> -
>  /* Zero if the async mode, although enabled, is masked, which means
>     linux_nat_wait should behave as if async mode was off.  */
>  static int linux_nat_async_mask_value = 1;
> @@ -3205,7 +3202,7 @@ linux_nat_pid_to_str (ptid_t ptid)
>  static void
>  sigchld_handler (int signo)
>  {
> -  if (linux_nat_async_enabled
> +  if (target_async_permitted
>        && linux_nat_async_events_state != sigchld_sync
>        && signo == SIGCHLD)
>      /* It is *always* a bug to hit this.  */
> @@ -3992,45 +3989,15 @@ linux_trad_target (CORE_ADDR 
> (*register_u_offset)(struct gdbarch *, int, int))
>    return t;
>  }
>  
> -/* Controls if async mode is permitted.  */
> -static int linux_async_permitted = 0;
> -
> -/* The set command writes to this variable.  If the inferior is
> -   executing, linux_nat_async_permitted is *not* updated.  */
> -static int linux_async_permitted_1 = 0;
> -
> -static void
> -set_maintenance_linux_async_permitted (char *args, int from_tty,
> -			       struct cmd_list_element *c)
> -{
> -  if (target_has_execution)
> -    {
> -      linux_async_permitted_1 = linux_async_permitted;
> -      error (_("Cannot change this setting while the 
> inferior is running."));
> -    }
> -
> -  linux_async_permitted = linux_async_permitted_1;
> -  linux_nat_set_async_mode (linux_async_permitted);
> -}
> -
> -static void
> -show_maintenance_linux_async_permitted (struct ui_file 
> *file, int from_tty,
> -			    struct cmd_list_element *c, const 
> char *value)
> -{
> -  fprintf_filtered (file, _("\
> -Controlling the GNU/Linux inferior in asynchronous mode is %s.\n"),
> -		    value);
> -}
> -
>  /* target_is_async_p implementation.  */
>  
>  static int
>  linux_nat_is_async_p (void)
>  {
>    /* NOTE: palves 2008-03-21: We're only async when the user requests
> -     it explicitly with the "maintenance set linux-async" command.
> +     it explicitly with the "maintenance set target-async" command.
>       Someday, linux will always be async.  */
> -  if (!linux_async_permitted)
> +  if (!target_async_permitted)
>      return 0;
>  
>    return 1;
> @@ -4042,9 +4009,9 @@ static int
>  linux_nat_can_async_p (void)
>  {
>    /* NOTE: palves 2008-03-21: We're only async when the user requests
> -     it explicitly with the "maintenance set linux-async" command.
> +     it explicitly with the "maintenance set target-async" command.
>       Someday, linux will always be async.  */
> -  if (!linux_async_permitted)
> +  if (!target_async_permitted)
>      return 0;
>  
>    /* See target.h/target_async_mask.  */
> @@ -4125,7 +4092,7 @@ get_pending_events (void)
>  {
>    int status, options, pid;
>  
> -  if (!linux_nat_async_enabled
> +  if (!target_async_permitted
>        || linux_nat_async_events_state != sigchld_async)
>      internal_error (__FILE__, __LINE__,
>  		    "get_pending_events called with async masked");
> @@ -4329,7 +4296,7 @@ static void
>  linux_nat_async (void (*callback) (enum inferior_event_type 
> event_type,
>  				   void *context), void *context)
>  {
> -  if (linux_nat_async_mask_value == 0 || !linux_nat_async_enabled)
> +  if (linux_nat_async_mask_value == 0 || !target_async_permitted)
>      internal_error (__FILE__, __LINE__,
>  		    "Calling target_async when async is masked");
>  
> @@ -4353,35 +4320,6 @@ linux_nat_async (void (*callback) 
> (enum inferior_event_type event_type,
>    return;
>  }
>  
> -/* Enable/Disable async mode.  */
> -
> -static void
> -linux_nat_set_async_mode (int on)
> -{
> -  if (linux_nat_async_enabled != on)
> -    {
> -      if (on)
> -	{
> -	  gdb_assert (waitpid_queue == NULL);
> -	  if (pipe (linux_nat_event_pipe) == -1)
> -	    internal_error (__FILE__, __LINE__,
> -			    "creating event pipe failed.");
> -	  fcntl (linux_nat_event_pipe[0], F_SETFL, O_NONBLOCK);
> -	  fcntl (linux_nat_event_pipe[1], F_SETFL, O_NONBLOCK);
> -	}
> -      else
> -	{
> -	  drain_queued_events (-1);
> -	  linux_nat_num_queued_events = 0;
> -	  close (linux_nat_event_pipe[0]);
> -	  close (linux_nat_event_pipe[1]);
> -	  linux_nat_event_pipe[0] = linux_nat_event_pipe[1] = -1;
> -
> -	}
> -    }
> -  linux_nat_async_enabled = on;
> -}
> -
>  static int
>  send_sigint_callback (struct lwp_info *lp, void *data)
>  {
> @@ -4478,6 +4416,18 @@ linux_nat_get_siginfo (ptid_t ptid)
>    return &lp->siginfo;
>  }
>  
> +/* Enable/Disable async mode.  */
> +
> +static void
> +linux_nat_setup_async (void)
> +{
> +  if (pipe (linux_nat_event_pipe) == -1)
> +    internal_error (__FILE__, __LINE__,
> +		    "creating event pipe failed.");
> +  fcntl (linux_nat_event_pipe[0], F_SETFL, O_NONBLOCK);
> +  fcntl (linux_nat_event_pipe[1], F_SETFL, O_NONBLOCK);
> +}
> +
>  void
>  _initialize_linux_nat (void)
>  {
> @@ -4510,16 +4460,6 @@ Enables printf debugging output."),
>  			    show_debug_linux_nat_async,
>  			    &setdebuglist, &showdebuglist);
>  
> -  add_setshow_boolean_cmd ("linux-async", class_maintenance,
> -			   &linux_async_permitted_1, _("\
> -Set whether gdb controls the GNU/Linux inferior in 
> asynchronous mode."), _("\
> -Show whether gdb controls the GNU/Linux inferior in 
> asynchronous mode."), _("\
> -Tells gdb whether to control the GNU/Linux inferior in 
> asynchronous mode."),
> -			   set_maintenance_linux_async_permitted,
> -			   show_maintenance_linux_async_permitted,
> -			   &maintenance_set_cmdlist,
> -			   &maintenance_show_cmdlist);
> -
>    /* Get the default SIGCHLD action.  Used while forking an inferior
>       (see linux_nat_create_inferior/linux_nat_async_events).  */
>    sigaction (SIGCHLD, NULL, &sigchld_default_action);
> @@ -4551,8 +4491,7 @@ Tells gdb whether to control the 
> GNU/Linux inferior in asynchronous mode."),
>    sigemptyset (&async_sigchld_action.sa_mask);
>    async_sigchld_action.sa_flags = SA_RESTART;
>  
> -  /* Install the default mode.  */
> -  linux_nat_set_async_mode (linux_async_permitted);
> +  linux_nat_setup_async ();
>  
>    add_setshow_boolean_cmd ("disable-randomization", class_support,
>  			   &disable_randomization, _("\
> diff --git a/gdb/mi/mi-cmds.c b/gdb/mi/mi-cmds.c
> index 3ae4c95..ca0f428 100644
> --- a/gdb/mi/mi-cmds.c
> +++ b/gdb/mi/mi-cmds.c
> @@ -89,6 +89,7 @@ struct mi_cmd mi_cmds[] =
>    { "inferior-tty-show", { NULL, 0 }, mi_cmd_inferior_tty_show},
>    { "interpreter-exec", { NULL, 0 }, mi_cmd_interpreter_exec},
>    { "list-features", { NULL, 0 }, mi_cmd_list_features},
> +  { "list-target-features", { NULL, 0 }, 
> mi_cmd_list_target_features},
>    { "overlay-auto", { NULL, 0 }, NULL },
>    { "overlay-list-mapping-state", { NULL, 0 }, NULL },
>    { "overlay-list-overlays", { NULL, 0 }, NULL },
> diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> index 72e18c7..16887ae 100644
> --- a/gdb/mi/mi-cmds.h
> +++ b/gdb/mi/mi-cmds.h
> @@ -66,6 +66,7 @@ extern mi_cmd_argv_ftype mi_cmd_inferior_tty_set;
>  extern mi_cmd_argv_ftype mi_cmd_inferior_tty_show;
>  extern mi_cmd_argv_ftype mi_cmd_interpreter_exec;
>  extern mi_cmd_argv_ftype mi_cmd_list_features;
> +extern mi_cmd_argv_ftype mi_cmd_list_target_features;
>  extern mi_cmd_argv_ftype mi_cmd_stack_info_depth;
>  extern mi_cmd_argv_ftype mi_cmd_stack_info_frame;
>  extern mi_cmd_argv_ftype mi_cmd_stack_list_args;
> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index 733fc47..b18326d 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -915,7 +915,25 @@ mi_cmd_list_features (char *command, 
> char **argv, int argc)
>  
>    error ("-list-features should be passed no arguments");
>  }
> - 
> +
> +void
> +mi_cmd_list_target_features (char *command, char **argv, int argc)
> +{
> +  if (argc == 0)
> +    {
> +      struct cleanup *cleanup = NULL;
> +      cleanup = make_cleanup_ui_out_list_begin_end (uiout, 
> "features");      
> +
> +      if (target_can_async_p ())
> +	ui_out_field_string (uiout, NULL, "async");
> +      
> +      do_cleanups (cleanup);
> +      return;
> +    }
> +
> +  error ("-list-target-features should be passed no arguments");
> +}
> +
>  /* Execute a command within a safe environment.
>     Return <0 for error; >=0 for ok.
>  
> diff --git a/gdb/remote.c b/gdb/remote.c
> index 2782d05..af3b0b8 100644
> --- a/gdb/remote.c
> +++ b/gdb/remote.c
> @@ -209,33 +209,6 @@ static void 
> show_remote_protocol_packet_cmd (struct ui_file *file,
>  
>  void _initialize_remote (void);
>  
> -/* Controls if async mode is permitted.  */
> -static int remote_async_permitted = 0;
> -
> -static int remote_async_permitted_set = 0;
> -
> -static void
> -set_maintenance_remote_async_permitted (char *args, int from_tty,
> -					struct cmd_list_element *c)
> -{
> -  if (target_has_execution)
> -    {
> -      remote_async_permitted_set = remote_async_permitted; 
> /* revert */
> -      error (_("Cannot change this setting while the 
> inferior is running."));
> -    }
> -
> -  remote_async_permitted = remote_async_permitted_set;
> -}
> -
> -static void
> -show_maintenance_remote_async_permitted (struct ui_file 
> *file, int from_tty,
> -					 struct 
> cmd_list_element *c, const char *value)
> -{
> -  fprintf_filtered (file, _("\
> -Controlling the remote inferior in asynchronous mode is %s.\n"),
> -		    value);
> -}
> -
>  /* For "remote".  */
>  
>  static struct cmd_list_element *remote_cmdlist;
> @@ -2703,7 +2676,7 @@ remote_open_1 (char *name, int 
> from_tty, struct target_ops *target, int extended
>  	   "(e.g. /dev/ttyS0, /dev/ttya, COM1, etc.)."));
>  
>    /* See FIXME above.  */
> -  if (!remote_async_permitted)
> +  if (!target_async_permitted)
>      wait_forever_enabled_p = 1;
>  
>    /* If we're connected to a running target, target_preopen 
> will kill it.
> @@ -2824,7 +2797,7 @@ remote_open_1 (char *name, int 
> from_tty, struct target_ops *target, int extended
>       this before anything involving memory or registers.  */
>    target_find_description ();
>  
> -  if (remote_async_permitted)
> +  if (target_async_permitted)
>      {
>        /* With this target we start out by owning the terminal.  */
>        remote_async_terminal_ours_p = 1;
> @@ -2869,13 +2842,13 @@ remote_open_1 (char *name, int 
> from_tty, struct target_ops *target, int extended
>      if (ex.reason < 0)
>        {
>  	pop_target ();
> -	if (remote_async_permitted)
> +	if (target_async_permitted)
>  	  wait_forever_enabled_p = 1;
>  	throw_exception (ex);
>        }
>    }
>  
> -  if (remote_async_permitted)
> +  if (target_async_permitted)
>      wait_forever_enabled_p = 1;
>  
>    if (extended_p)
> @@ -3403,7 +3376,7 @@ Give up (and stop debugging it)? "))
>  static void
>  remote_terminal_inferior (void)
>  {
> -  if (!remote_async_permitted)
> +  if (!target_async_permitted)
>      /* Nothing to do.  */
>      return;
>  
> @@ -3433,7 +3406,7 @@ remote_terminal_inferior (void)
>  static void
>  remote_terminal_ours (void)
>  {
> -  if (!remote_async_permitted)
> +  if (!target_async_permitted)
>      /* Nothing to do.  */
>      return;
>  
> @@ -7265,7 +7238,7 @@ Specify the serial device it is 
> connected to (e.g. /dev/ttya).";
>  static int
>  remote_can_async_p (void)
>  {
> -  if (!remote_async_permitted)
> +  if (!target_async_permitted)
>      /* We only enable async when the user specifically asks 
> for it.  */
>      return 0;
>  
> @@ -7276,7 +7249,7 @@ remote_can_async_p (void)
>  static int
>  remote_is_async_p (void)
>  {
> -  if (!remote_async_permitted)
> +  if (!target_async_permitted)
>      /* We only enable async when the user specifically asks 
> for it.  */
>      return 0;
>  
> @@ -7630,17 +7603,6 @@ Set the remote pathname for \"run\""), _("\
>  Show the remote pathname for \"run\""), NULL, NULL, NULL,
>  				   &remote_set_cmdlist, 
> &remote_show_cmdlist);
>  
> -  add_setshow_boolean_cmd ("remote-async", class_maintenance,
> -			   &remote_async_permitted_set, _("\
> -Set whether gdb controls the remote inferior in asynchronous 
> mode."), _("\
> -Show whether gdb controls the remote inferior in 
> asynchronous mode."), _("\
> -Tells gdb whether to control the remote inferior in 
> asynchronous mode."),
> -			   set_maintenance_remote_async_permitted,
> -			   show_maintenance_remote_async_permitted,
> -			   &maintenance_set_cmdlist,
> -			   &maintenance_show_cmdlist);
> -
> -
>    /* Eventually initialize fileio.  See fileio.c */
>    initialize_remote_fileio (remote_set_cmdlist, remote_show_cmdlist);
>  
> diff --git a/gdb/target.c b/gdb/target.c
> index 6cda095..0dbe49b 100644
> --- a/gdb/target.c
> +++ b/gdb/target.c
> @@ -3136,6 +3136,35 @@ maintenance_print_target_stack (char 
> *cmd, int from_tty)
>      }
>  }
>  
> +/* Controls if async mode is permitted.  */
> +int target_async_permitted = 0;
> +
> +/* The set command writes to this variable.  If the inferior is
> +   executing, linux_nat_async_permitted is *not* updated.  */
> +static int target_async_permitted_1 = 0;
> +
> +static void
> +set_maintenance_target_async_permitted (char *args, int from_tty,
> +					struct cmd_list_element *c)
> +{
> +  if (target_has_execution)
> +    {
> +      target_async_permitted_1 = target_async_permitted;
> +      error (_("Cannot change this setting while the 
> inferior is running."));
> +    }
> +
> +  target_async_permitted = target_async_permitted_1;
> +}
> +
> +static void
> +show_maintenance_target_async_permitted (struct ui_file 
> *file, int from_tty,
> +					 struct cmd_list_element *c,
> +					 const char *value)
> +{
> +  fprintf_filtered (file, _("\
> +Controlling the inferior in asynchronous mode is %s.\n"), value);
> +}
> +
>  void
>  initialize_targets (void)
>  {
> @@ -3173,5 +3202,15 @@ result in significant performance 
> improvement for remote targets."),
>             _("Print the name of each layer of the internal 
> target stack."),
>             &maintenanceprintlist);
>  
> +  add_setshow_boolean_cmd ("target-async", no_class,
> +			   &target_async_permitted_1, _("\
> +Set whether gdb controls the inferior in asynchronous mode."), _("\
> +Show whether gdb controls the inferior in asynchronous mode."), _("\
> +Tells gdb whether to control the inferior in asynchronous mode."),
> +			   set_maintenance_target_async_permitted,
> +			   show_maintenance_target_async_permitted,
> +			   &setlist,
> +			   &showlist);
> +
>    target_dcache = dcache_init ();
>  }
> diff --git a/gdb/target.h b/gdb/target.h
> index e242566..3a1d4b7 100644
> --- a/gdb/target.h
> +++ b/gdb/target.h
> @@ -956,6 +956,10 @@ int target_follow_fork (int follow_child);
>  #define target_can_lock_scheduler \
>       (current_target.to_has_thread_control & tc_schedlock)
>  
> +/* Should the target enable async mode if it is supported?  Temporary
> +   cludge until async mode is a strict superset of sync mode.  */
> +extern int target_async_permitted;
> +
>  /* Can the target support asynchronous execution? */
>  #define target_can_async_p() (current_target.to_can_async_p ())
>  
> diff --git a/gdb/testsuite/gdb.mi/mi-async.exp 
> b/gdb/testsuite/gdb.mi/mi-async.exp
> index 9ac91fd..a251c32 100644
> --- a/gdb/testsuite/gdb.mi/mi-async.exp
> +++ b/gdb/testsuite/gdb.mi/mi-async.exp
> @@ -27,7 +27,7 @@ if { !([isnative] && [istarget *-linux*]) \
>  
>  # The plan is for async mode to become the default but 
> toggle for now.
>  set saved_gdbflags $GDBFLAGS
> -set GDBFLAGS [concat $GDBFLAGS " -ex \"maint set linux-async on\""]
> +set GDBFLAGS [concat $GDBFLAGS " -ex \"set target-async on\""]
>  
>  load_lib mi-support.exp
>  
> diff --git a/gdb/testsuite/lib/mi-support.exp 
> b/gdb/testsuite/lib/mi-support.exp
> index 762e4e2..09d3eeb 100644
> --- a/gdb/testsuite/lib/mi-support.exp
> +++ b/gdb/testsuite/lib/mi-support.exp
> @@ -912,10 +912,10 @@ proc detect_async {} {
>      global async
>      global mi_gdb_prompt
>  
> -    send_gdb "maint show linux-async\n"
> +    send_gdb "show target-async\n"
>          
>      gdb_expect {
> -        -re ".*Controlling the GNU/Linux inferior in 
> asynchronous mode is on...*$mi_gdb_prompt$" {
> +        -re ".*Controlling the inferior in asynchronous mode 
> is on...*$mi_gdb_prompt$" {
>              set async 1
>          }
>          -re ".*$mi_gdb_prompt$" {
> -- 
> 1.5.3.5
> 
> 

Re: [RFA] Unify async setting.

[Vladimir Prus]

On Friday 15 August 2008 21:29:47 Marc Khouzam wrote:
> Hi,
> 
> it think it is great to have a single command to set async for native
> or targets.
> Will the command be 'set async' or 'set target-async', the patch
> seems to use target-async.

'target-async' it will be. (today, I seem to beat my personal records of
meaning one thing and saying another).

- Volodya

Re: [RFA] Unify async setting.

[Daniel Jacobowitz]

On Fri, Aug 15, 2008 at 09:07:19PM +0400, Vladimir Prus wrote:
> 
> Presently, one need to use different commands to request async mode for linux
> native and for async targets, which is hard on frontends.  Furthermore, the
> relevant variables merely *allow* async mode, and there's no way for frontend
> to make sure that async mode is actually in effect. This patch makes two things:
> 
> - Converts target-specific variables into a single 'set async' command.
> - Adds new MI -list-target-features command that allows to check if current
> target is in async mode.
> 
> The bulk of the patch is actually written by Pedro, I've only added MI/testsuite/doc
> bits.
> 
> OK?

OK with Eli's comments, except check for references to "maintenance";
it's not a maintenance command any more.  And the "set async"
reference in the doc that Marc noticed.  Is there a NEWS entry that
needs updating or is that still to be written?

-- 
Daniel Jacobowitz
CodeSourcery

Re: [RFA] Unify async setting.

[Vladimir Prus]

[-- Attachment #1: Type: text/plain, Size: 1048 bytes --]

Daniel Jacobowitz wrote:

> On Fri, Aug 15, 2008 at 09:07:19PM +0400, Vladimir Prus wrote:
>> 
>> Presently, one need to use different commands to request async mode for linux
>> native and for async targets, which is hard on frontends.  Furthermore, the
>> relevant variables merely *allow* async mode, and there's no way for frontend
>> to make sure that async mode is actually in effect. This patch makes two things:
>> 
>> - Converts target-specific variables into a single 'set async' command.
>> - Adds new MI -list-target-features command that allows to check if current
>> target is in async mode.
>> 
>> The bulk of the patch is actually written by Pedro, I've only added MI/testsuite/doc
>> bits.
>> 
>> OK?
> 
> OK with Eli's comments, except check for references to "maintenance";
> it's not a maintenance command any more.  And the "set async"
> reference in the doc that Marc noticed.  Is there a NEWS entry that
> needs updating or is that still to be written?

I've checked in the below. I'll address NEWS immediately.

- Volodya



[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: final.diff --]
[-- Type: text/x-diff; name="final.diff", Size: 19276 bytes --]

commit 9f1afb3e2925135090e18f40b7539e1f444589bf
Author: Vladimir Prus <vladimir@codesourcery.com>
Date:   Thu Aug 14 16:30:08 2008 +0400

    Unify async setting.
    
    	* target.c (target_async_permitted, target_async_permitted_1)
    	(set_maintenance_target_async_permitted)
    	(show_maintenance_target_async_permitted): New.
    	(initialize_targets): Register 'set target-async'.
    	* target.h (target_async_permitted): Declare.
    	* linux-nat.c (linux_nat_async_enabled)
    	(linux_nat_async_permitted, set_maintenance_linux_async_permitted)
    	(show_maintenance_linux_async_permitted): Remove.
    	(sigchld_handler, linux_nat_is_async_p, linux_nat_can_async_p)
    	(get_pending_events, linux_nat_async): Use target_async_permitted.
    	(linux_nat_set_async_mode): Remove, moving the only used bits
    	into...
    	(linux_nat_setup_async): This.
    	(_initialize_linux_nat): Do not register 'maint set linux-async'.
    	Use linux_nat_setup_async.
    	* remote.c (remote_async_permitted, remote_async_permitted_set)
    	(set_maintenance_remote_async_permitted)
    	(show_maintenance_remote_async_permitted): Remove.
    	(remote_open_1, remote_terminal_inferior, remote_can_async_p)
    	(remote_is_async_p): Use target_async_permitted.
    	(_initialize_remote): Don't register 'main set remote-async'.
    	* mi/mi-cmds.c (mi_cmds): Register -list-target-features.
    	* mi/mi-cmds.h (mi_cmd_list_target_features): New.
    	* mi/mi-main.c (mi_cmd_list_target_features): New.
    
    	[testsuite/ChangeLog]
    	* gdb.mi/mi-async.exp: Use 'set target-async'.
    	* lib/mi-support.exp: Use 'set/show target-async'.
    
    	[doc/ChangeLog]
    	* gdb.texinfo (Background execution): Adjust example
    	(GDB/MI Miscellaneous Commands): Document -list-target-features.

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 21648b7..100d795 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -4572,12 +4572,9 @@ independently and simultaneously.
 To enter non-stop mode, use this sequence of commands before you run
 or attach to your program:
 
-@c FIXME: can we fix this recipe to avoid the linux-async/remote-async details?
-
 @smallexample
 # Enable the async interface.  
-# For target remote, use remote-async instead of linux-async.
-maint set linux-async 1
+set target-async 1
 
 # If using the CLI, pagination breaks non-stop.
 set pagination off
@@ -4710,7 +4707,7 @@ use @code{interrupt -a}.
 @end table
 
 You may need to explicitly enable async mode before you can use background
-execution commands.  @xref{Maintenance Commands}, for details.  If the
+execution commands, with the @code{set target-async 1} command.  If the
 target doesn't support async mode, @value{GDBN} issues an error message
 if you attempt to use the background execution commands.
 
@@ -22640,6 +22637,34 @@ option to the @code{-break-insert} command.
 
 @end itemize
 
+@subheading The @code{-list-target-features} Command
+@findex -list-target-features
+
+Returns a list of particular features that are supported by the
+target.  Those features affect the permitted MI commands, but 
+unlike the features reported by the @code{-list-features} command, the
+features depend on which target GDB is using at the moment.  Whenever
+a target can change, due to commands such as @code{-target-select},
+@code{-target-attach} or @code{-exec-run}, the list of target features
+may change, and the frontend should obtain it again.
+Example output:
+
+@smallexample
+(gdb) -list-features
+^done,result=["async"]
+@end smallexample
+
+The current list of features is:
+
+@table @samp
+@item async
+Indicates that the target is capable of asynchronous command
+execution, which means that @value{GDBN} will accept further commands
+while the target is running.
+
+@end table
+
+
 @subheading The @code{-interpreter-exec} Command
 @findex -interpreter-exec
 
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index b59a35c..b25104e 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -276,9 +276,6 @@ static int linux_supports_tracevforkdone_flag = -1;
 
 /* Async mode support */
 
-/* True if async mode is currently on.  */
-static int linux_nat_async_enabled;
-
 /* Zero if the async mode, although enabled, is masked, which means
    linux_nat_wait should behave as if async mode was off.  */
 static int linux_nat_async_mask_value = 1;
@@ -3205,7 +3202,7 @@ linux_nat_pid_to_str (ptid_t ptid)
 static void
 sigchld_handler (int signo)
 {
-  if (linux_nat_async_enabled
+  if (target_async_permitted
       && linux_nat_async_events_state != sigchld_sync
       && signo == SIGCHLD)
     /* It is *always* a bug to hit this.  */
@@ -3992,45 +3989,15 @@ linux_trad_target (CORE_ADDR (*register_u_offset)(struct gdbarch *, int, int))
   return t;
 }
 
-/* Controls if async mode is permitted.  */
-static int linux_async_permitted = 0;
-
-/* The set command writes to this variable.  If the inferior is
-   executing, linux_nat_async_permitted is *not* updated.  */
-static int linux_async_permitted_1 = 0;
-
-static void
-set_maintenance_linux_async_permitted (char *args, int from_tty,
-			       struct cmd_list_element *c)
-{
-  if (target_has_execution)
-    {
-      linux_async_permitted_1 = linux_async_permitted;
-      error (_("Cannot change this setting while the inferior is running."));
-    }
-
-  linux_async_permitted = linux_async_permitted_1;
-  linux_nat_set_async_mode (linux_async_permitted);
-}
-
-static void
-show_maintenance_linux_async_permitted (struct ui_file *file, int from_tty,
-			    struct cmd_list_element *c, const char *value)
-{
-  fprintf_filtered (file, _("\
-Controlling the GNU/Linux inferior in asynchronous mode is %s.\n"),
-		    value);
-}
-
 /* target_is_async_p implementation.  */
 
 static int
 linux_nat_is_async_p (void)
 {
   /* NOTE: palves 2008-03-21: We're only async when the user requests
-     it explicitly with the "maintenance set linux-async" command.
+     it explicitly with the "maintenance set target-async" command.
      Someday, linux will always be async.  */
-  if (!linux_async_permitted)
+  if (!target_async_permitted)
     return 0;
 
   return 1;
@@ -4042,9 +4009,9 @@ static int
 linux_nat_can_async_p (void)
 {
   /* NOTE: palves 2008-03-21: We're only async when the user requests
-     it explicitly with the "maintenance set linux-async" command.
+     it explicitly with the "maintenance set target-async" command.
      Someday, linux will always be async.  */
-  if (!linux_async_permitted)
+  if (!target_async_permitted)
     return 0;
 
   /* See target.h/target_async_mask.  */
@@ -4125,7 +4092,7 @@ get_pending_events (void)
 {
   int status, options, pid;
 
-  if (!linux_nat_async_enabled
+  if (!target_async_permitted
       || linux_nat_async_events_state != sigchld_async)
     internal_error (__FILE__, __LINE__,
 		    "get_pending_events called with async masked");
@@ -4329,7 +4296,7 @@ static void
 linux_nat_async (void (*callback) (enum inferior_event_type event_type,
 				   void *context), void *context)
 {
-  if (linux_nat_async_mask_value == 0 || !linux_nat_async_enabled)
+  if (linux_nat_async_mask_value == 0 || !target_async_permitted)
     internal_error (__FILE__, __LINE__,
 		    "Calling target_async when async is masked");
 
@@ -4353,35 +4320,6 @@ linux_nat_async (void (*callback) (enum inferior_event_type event_type,
   return;
 }
 
-/* Enable/Disable async mode.  */
-
-static void
-linux_nat_set_async_mode (int on)
-{
-  if (linux_nat_async_enabled != on)
-    {
-      if (on)
-	{
-	  gdb_assert (waitpid_queue == NULL);
-	  if (pipe (linux_nat_event_pipe) == -1)
-	    internal_error (__FILE__, __LINE__,
-			    "creating event pipe failed.");
-	  fcntl (linux_nat_event_pipe[0], F_SETFL, O_NONBLOCK);
-	  fcntl (linux_nat_event_pipe[1], F_SETFL, O_NONBLOCK);
-	}
-      else
-	{
-	  drain_queued_events (-1);
-	  linux_nat_num_queued_events = 0;
-	  close (linux_nat_event_pipe[0]);
-	  close (linux_nat_event_pipe[1]);
-	  linux_nat_event_pipe[0] = linux_nat_event_pipe[1] = -1;
-
-	}
-    }
-  linux_nat_async_enabled = on;
-}
-
 static int
 send_sigint_callback (struct lwp_info *lp, void *data)
 {
@@ -4478,6 +4416,18 @@ linux_nat_get_siginfo (ptid_t ptid)
   return &lp->siginfo;
 }
 
+/* Enable/Disable async mode.  */
+
+static void
+linux_nat_setup_async (void)
+{
+  if (pipe (linux_nat_event_pipe) == -1)
+    internal_error (__FILE__, __LINE__,
+		    "creating event pipe failed.");
+  fcntl (linux_nat_event_pipe[0], F_SETFL, O_NONBLOCK);
+  fcntl (linux_nat_event_pipe[1], F_SETFL, O_NONBLOCK);
+}
+
 void
 _initialize_linux_nat (void)
 {
@@ -4510,16 +4460,6 @@ Enables printf debugging output."),
 			    show_debug_linux_nat_async,
 			    &setdebuglist, &showdebuglist);
 
-  add_setshow_boolean_cmd ("linux-async", class_maintenance,
-			   &linux_async_permitted_1, _("\
-Set whether gdb controls the GNU/Linux inferior in asynchronous mode."), _("\
-Show whether gdb controls the GNU/Linux inferior in asynchronous mode."), _("\
-Tells gdb whether to control the GNU/Linux inferior in asynchronous mode."),
-			   set_maintenance_linux_async_permitted,
-			   show_maintenance_linux_async_permitted,
-			   &maintenance_set_cmdlist,
-			   &maintenance_show_cmdlist);
-
   /* Get the default SIGCHLD action.  Used while forking an inferior
      (see linux_nat_create_inferior/linux_nat_async_events).  */
   sigaction (SIGCHLD, NULL, &sigchld_default_action);
@@ -4551,8 +4491,7 @@ Tells gdb whether to control the GNU/Linux inferior in asynchronous mode."),
   sigemptyset (&async_sigchld_action.sa_mask);
   async_sigchld_action.sa_flags = SA_RESTART;
 
-  /* Install the default mode.  */
-  linux_nat_set_async_mode (linux_async_permitted);
+  linux_nat_setup_async ();
 
   add_setshow_boolean_cmd ("disable-randomization", class_support,
 			   &disable_randomization, _("\
diff --git a/gdb/mi/mi-cmds.c b/gdb/mi/mi-cmds.c
index 3ae4c95..ca0f428 100644
--- a/gdb/mi/mi-cmds.c
+++ b/gdb/mi/mi-cmds.c
@@ -89,6 +89,7 @@ struct mi_cmd mi_cmds[] =
   { "inferior-tty-show", { NULL, 0 }, mi_cmd_inferior_tty_show},
   { "interpreter-exec", { NULL, 0 }, mi_cmd_interpreter_exec},
   { "list-features", { NULL, 0 }, mi_cmd_list_features},
+  { "list-target-features", { NULL, 0 }, mi_cmd_list_target_features},
   { "overlay-auto", { NULL, 0 }, NULL },
   { "overlay-list-mapping-state", { NULL, 0 }, NULL },
   { "overlay-list-overlays", { NULL, 0 }, NULL },
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index 72e18c7..16887ae 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -66,6 +66,7 @@ extern mi_cmd_argv_ftype mi_cmd_inferior_tty_set;
 extern mi_cmd_argv_ftype mi_cmd_inferior_tty_show;
 extern mi_cmd_argv_ftype mi_cmd_interpreter_exec;
 extern mi_cmd_argv_ftype mi_cmd_list_features;
+extern mi_cmd_argv_ftype mi_cmd_list_target_features;
 extern mi_cmd_argv_ftype mi_cmd_stack_info_depth;
 extern mi_cmd_argv_ftype mi_cmd_stack_info_frame;
 extern mi_cmd_argv_ftype mi_cmd_stack_list_args;
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index 30e62f6..332ce42 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -915,7 +915,25 @@ mi_cmd_list_features (char *command, char **argv, int argc)
 
   error ("-list-features should be passed no arguments");
 }
- 
+
+void
+mi_cmd_list_target_features (char *command, char **argv, int argc)
+{
+  if (argc == 0)
+    {
+      struct cleanup *cleanup = NULL;
+      cleanup = make_cleanup_ui_out_list_begin_end (uiout, "features");      
+
+      if (target_can_async_p ())
+	ui_out_field_string (uiout, NULL, "async");
+      
+      do_cleanups (cleanup);
+      return;
+    }
+
+  error ("-list-target-features should be passed no arguments");
+}
+
 /* Execute a command within a safe environment.
    Return <0 for error; >=0 for ok.
 
diff --git a/gdb/remote.c b/gdb/remote.c
index 2782d05..af3b0b8 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -209,33 +209,6 @@ static void show_remote_protocol_packet_cmd (struct ui_file *file,
 
 void _initialize_remote (void);
 
-/* Controls if async mode is permitted.  */
-static int remote_async_permitted = 0;
-
-static int remote_async_permitted_set = 0;
-
-static void
-set_maintenance_remote_async_permitted (char *args, int from_tty,
-					struct cmd_list_element *c)
-{
-  if (target_has_execution)
-    {
-      remote_async_permitted_set = remote_async_permitted; /* revert */
-      error (_("Cannot change this setting while the inferior is running."));
-    }
-
-  remote_async_permitted = remote_async_permitted_set;
-}
-
-static void
-show_maintenance_remote_async_permitted (struct ui_file *file, int from_tty,
-					 struct cmd_list_element *c, const char *value)
-{
-  fprintf_filtered (file, _("\
-Controlling the remote inferior in asynchronous mode is %s.\n"),
-		    value);
-}
-
 /* For "remote".  */
 
 static struct cmd_list_element *remote_cmdlist;
@@ -2703,7 +2676,7 @@ remote_open_1 (char *name, int from_tty, struct target_ops *target, int extended
 	   "(e.g. /dev/ttyS0, /dev/ttya, COM1, etc.)."));
 
   /* See FIXME above.  */
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     wait_forever_enabled_p = 1;
 
   /* If we're connected to a running target, target_preopen will kill it.
@@ -2824,7 +2797,7 @@ remote_open_1 (char *name, int from_tty, struct target_ops *target, int extended
      this before anything involving memory or registers.  */
   target_find_description ();
 
-  if (remote_async_permitted)
+  if (target_async_permitted)
     {
       /* With this target we start out by owning the terminal.  */
       remote_async_terminal_ours_p = 1;
@@ -2869,13 +2842,13 @@ remote_open_1 (char *name, int from_tty, struct target_ops *target, int extended
     if (ex.reason < 0)
       {
 	pop_target ();
-	if (remote_async_permitted)
+	if (target_async_permitted)
 	  wait_forever_enabled_p = 1;
 	throw_exception (ex);
       }
   }
 
-  if (remote_async_permitted)
+  if (target_async_permitted)
     wait_forever_enabled_p = 1;
 
   if (extended_p)
@@ -3403,7 +3376,7 @@ Give up (and stop debugging it)? "))
 static void
 remote_terminal_inferior (void)
 {
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     /* Nothing to do.  */
     return;
 
@@ -3433,7 +3406,7 @@ remote_terminal_inferior (void)
 static void
 remote_terminal_ours (void)
 {
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     /* Nothing to do.  */
     return;
 
@@ -7265,7 +7238,7 @@ Specify the serial device it is connected to (e.g. /dev/ttya).";
 static int
 remote_can_async_p (void)
 {
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     /* We only enable async when the user specifically asks for it.  */
     return 0;
 
@@ -7276,7 +7249,7 @@ remote_can_async_p (void)
 static int
 remote_is_async_p (void)
 {
-  if (!remote_async_permitted)
+  if (!target_async_permitted)
     /* We only enable async when the user specifically asks for it.  */
     return 0;
 
@@ -7630,17 +7603,6 @@ Set the remote pathname for \"run\""), _("\
 Show the remote pathname for \"run\""), NULL, NULL, NULL,
 				   &remote_set_cmdlist, &remote_show_cmdlist);
 
-  add_setshow_boolean_cmd ("remote-async", class_maintenance,
-			   &remote_async_permitted_set, _("\
-Set whether gdb controls the remote inferior in asynchronous mode."), _("\
-Show whether gdb controls the remote inferior in asynchronous mode."), _("\
-Tells gdb whether to control the remote inferior in asynchronous mode."),
-			   set_maintenance_remote_async_permitted,
-			   show_maintenance_remote_async_permitted,
-			   &maintenance_set_cmdlist,
-			   &maintenance_show_cmdlist);
-
-
   /* Eventually initialize fileio.  See fileio.c */
   initialize_remote_fileio (remote_set_cmdlist, remote_show_cmdlist);
 
diff --git a/gdb/target.c b/gdb/target.c
index 575415b..e469905 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -3133,6 +3133,35 @@ maintenance_print_target_stack (char *cmd, int from_tty)
     }
 }
 
+/* Controls if async mode is permitted.  */
+int target_async_permitted = 0;
+
+/* The set command writes to this variable.  If the inferior is
+   executing, linux_nat_async_permitted is *not* updated.  */
+static int target_async_permitted_1 = 0;
+
+static void
+set_maintenance_target_async_permitted (char *args, int from_tty,
+					struct cmd_list_element *c)
+{
+  if (target_has_execution)
+    {
+      target_async_permitted_1 = target_async_permitted;
+      error (_("Cannot change this setting while the inferior is running."));
+    }
+
+  target_async_permitted = target_async_permitted_1;
+}
+
+static void
+show_maintenance_target_async_permitted (struct ui_file *file, int from_tty,
+					 struct cmd_list_element *c,
+					 const char *value)
+{
+  fprintf_filtered (file, _("\
+Controlling the inferior in asynchronous mode is %s.\n"), value);
+}
+
 void
 initialize_targets (void)
 {
@@ -3170,5 +3199,15 @@ result in significant performance improvement for remote targets."),
            _("Print the name of each layer of the internal target stack."),
            &maintenanceprintlist);
 
+  add_setshow_boolean_cmd ("target-async", no_class,
+			   &target_async_permitted_1, _("\
+Set whether gdb controls the inferior in asynchronous mode."), _("\
+Show whether gdb controls the inferior in asynchronous mode."), _("\
+Tells gdb whether to control the inferior in asynchronous mode."),
+			   set_maintenance_target_async_permitted,
+			   show_maintenance_target_async_permitted,
+			   &setlist,
+			   &showlist);
+
   target_dcache = dcache_init ();
 }
diff --git a/gdb/target.h b/gdb/target.h
index ded91a2..350a7c4 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -956,6 +956,10 @@ int target_follow_fork (int follow_child);
 #define target_can_lock_scheduler \
      (current_target.to_has_thread_control & tc_schedlock)
 
+/* Should the target enable async mode if it is supported?  Temporary
+   cludge until async mode is a strict superset of sync mode.  */
+extern int target_async_permitted;
+
 /* Can the target support asynchronous execution? */
 #define target_can_async_p() (current_target.to_can_async_p ())
 
diff --git a/gdb/testsuite/gdb.mi/mi-async.exp b/gdb/testsuite/gdb.mi/mi-async.exp
index 9ac91fd..a251c32 100644
--- a/gdb/testsuite/gdb.mi/mi-async.exp
+++ b/gdb/testsuite/gdb.mi/mi-async.exp
@@ -27,7 +27,7 @@ if { !([isnative] && [istarget *-linux*]) \
 
 # The plan is for async mode to become the default but toggle for now.
 set saved_gdbflags $GDBFLAGS
-set GDBFLAGS [concat $GDBFLAGS " -ex \"maint set linux-async on\""]
+set GDBFLAGS [concat $GDBFLAGS " -ex \"set target-async on\""]
 
 load_lib mi-support.exp
 
diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index 762e4e2..09d3eeb 100644
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -912,10 +912,10 @@ proc detect_async {} {
     global async
     global mi_gdb_prompt
 
-    send_gdb "maint show linux-async\n"
+    send_gdb "show target-async\n"
         
     gdb_expect {
-        -re ".*Controlling the GNU/Linux inferior in asynchronous mode is on...*$mi_gdb_prompt$" {
+        -re ".*Controlling the inferior in asynchronous mode is on...*$mi_gdb_prompt$" {
             set async 1
         }
         -re ".*$mi_gdb_prompt$" {