[patch] gdbserver: qXfer multiprocess

[patch] gdbserver: qXfer multiprocess

[Aleksandar Ristovski]

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Hello,

This adds check for multiprocess before appending 
'multiprocess' to reply.

Thanks,

-- 
Aleksandar Ristovski
QNX Software Systems


ChangeLog:

* server.c (handle_query): Use multi_process and output
multiprocess accordingly.

[-- Attachment #2: gdbserver-server.c-multiprocess-20090615.diff --]
[-- Type: text/x-patch, Size: 605 bytes --]

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	15 Jun 2009 18:36:36 -0000
@@ -1106,7 +1106,8 @@ handle_query (char *own_buf, int packet_
       if (the_target->qxfer_osdata != NULL)
 	strcat (own_buf, ";qXfer:osdata:read+");
 
-      strcat (own_buf, ";multiprocess+");
+      if (multi_process)
+	strcat (own_buf, ";multiprocess+");
 
       if (target_supports_non_stop ())
 	strcat (own_buf, ";QNonStop+");

Re: [patch] gdbserver: qXfer multiprocess

[Pedro Alves]

On Tuesday 16 June 2009 21:10:14, Aleksandar Ristovski wrote:

> This adds check for multiprocess before appending 
> 'multiprocess' to reply.

I can see that from the patch.  But, why?

-- 
Pedro Alves

Re: [patch] gdbserver: qXfer multiprocess

[Aleksandar Ristovski]

Pedro Alves wrote:
> On Tuesday 16 June 2009 21:10:14, Aleksandar Ristovski wrote:
> 
>> This adds check for multiprocess before appending 
>> 'multiprocess' to reply.
> 
> I can see that from the patch.  But, why?
> 

If gdbserver doesn't have support for multiple processes, 
how will it report lack of that feature to GDB?

I have created gdbserver for nto to be able to use gdb for 
nto/linux. One of things this server will not have (at least 
for now) is multi process support. It will only handle one 
process a time.


-- 
Aleksandar Ristovski
QNX Software Systems

Re: [patch] gdbserver: qXfer multiprocess

[Pedro Alves]

On Wednesday 17 June 2009 01:56:06, Aleksandar Ristovski wrote:
> Pedro Alves wrote:
> > On Tuesday 16 June 2009 21:10:14, Aleksandar Ristovski wrote:
> > 
> >> This adds check for multiprocess before appending 
> >> 'multiprocess' to reply.
> > 
> > I can see that from the patch.  But, why?
> > 
> 
> If gdbserver doesn't have support for multiple processes, 
> how will it report lack of that feature to GDB?

By querying the target, how else?  Something like:

+      if (target_supports_multi_process ())
      strcat (own_buf, ";multiprocess+");

      if (target_supports_non_stop ())
	strcat (own_buf, ";QNonStop+");

(that function doesn't exist today, but it should).

> I have created gdbserver for nto to be able to use gdb for 
> nto/linux. One of things this server will not have (at least 
> for now) is multi process support. It will only handle one 
> process a time.

That is different from (like your patch was doing) reporting
multi_process support if GDB reports support as well, which is
still broken in your example.  (and now that you mention it,
in all gdbserver targets but linux).

-- 
Pedro Alves

Re: [patch] gdbserver: qXfer multiprocess

[Aleksandar Ristovski]

Pedro Alves wrote:
> On Wednesday 17 June 2009 01:56:06, Aleksandar Ristovski wrote:
>> Pedro Alves wrote:
>>> On Tuesday 16 June 2009 21:10:14, Aleksandar Ristovski wrote:
>>>
>>>> This adds check for multiprocess before appending 
>>>> 'multiprocess' to reply.
>>> I can see that from the patch.  But, why?
>>>
>> If gdbserver doesn't have support for multiple processes, 
>> how will it report lack of that feature to GDB?
> 
> By querying the target, how else?  Something like:
> 
> +      if (target_supports_multi_process ())
>       strcat (own_buf, ";multiprocess+");
> 
>       if (target_supports_non_stop ())
> 	strcat (own_buf, ";QNonStop+");
> 
> (that function doesn't exist today, but it should).
> 
>> I have created gdbserver for nto to be able to use gdb for 
>> nto/linux. One of things this server will not have (at least 
>> for now) is multi process support. It will only handle one 
>> process a time.
> 
> That is different from (like your patch was doing) reporting
> multi_process support if GDB reports support as well, which is
> still broken in your example.  (and now that you mention it,
> in all gdbserver targets but linux).
> 

Yes, I realized when I saw your question and revisited the code.

-- 
Aleksandar Ristovski
QNX Software Systems

Re: [patch] gdbserver: qXfer multiprocess

[Aleksandar Ristovski]

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Pedro Alves wrote:
> 
> By querying the target, how else?  Something like:
> 
> +      if (target_supports_multi_process ())
>       strcat (own_buf, ";multiprocess+");
> 

Here is a patch that does what you described.

Thanks,

-- 
Aleksandar Ristovski
QNX Software Systems

ChangeLog:

* 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.


[-- Attachment #2: gdbserver-supports_multiprocess-20090617.diff --]
[-- Type: text/x-patch, Size: 2243 bytes --]

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 17:12:04 -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 17:12:04 -0000
@@ -1106,7 +1106,8 @@ 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+");
 
       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 17:12:06 -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

Re: [patch] gdbserver: qXfer multiprocess

[Pedro Alves]

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').

-- 
Pedro Alves

Re: [patch] gdbserver: qXfer multiprocess

[Aleksandar Ristovski]

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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.


[-- Attachment #2: gdbserver-supports_multiprocess-20090617-1.diff --]
[-- Type: text/x-patch, Size: 2340 bytes --]

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

Re: [patch] gdbserver: qXfer multiprocess

[Pedro Alves]

On Wednesday 17 June 2009 20:05:38, Aleksandar Ristovski wrote:
> Pedro Alves wrote:

> > 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
> 
> Ok, then something like this?


> -      strcat (own_buf, ";multiprocess+");
> +      if (target_supports_multiprocess ())
> +         strcat (own_buf, ";multiprocess+");
> +      else
> +         /* Override GDB's ability to support multiprocess.  */
> +         multi_process = 0;

Indentation is off here.  I'd prefer if we didn't turn the
flag on at all in the first place.  Checked in as below.  Thanks.

-- 
Pedro Alves

	* target.h (struct target_ops) <supports_multi_process>: New
	callback.
	(target_supports_multi_process): New.
	* server.c (handle_query): Even if GDB reports support, only
	enable multi-process if the target also supports it.  Report
	multi-process support only if the target backend supports it.
	* linux-low.c (linux_supports_multi_process): New function.
	(linux_target_ops): Install it as target_supports_multi_process
	callback.

---
 gdb/gdbserver/linux-low.c |    7 +++++++
 gdb/gdbserver/server.c    |   11 ++++++++---
 gdb/gdbserver/target.h    |    7 +++++++
 3 files changed, 22 insertions(+), 3 deletions(-)

Index: src/gdb/gdbserver/target.h
===================================================================
--- src.orig/gdb/gdbserver/target.h	2009-06-19 14:26:36.000000000 +0100
+++ src/gdb/gdbserver/target.h	2009-06-19 14:34:09.000000000 +0100
@@ -275,6 +275,9 @@ struct target_ops
   /* Switch to non-stop (1) or all-stop (0) mode.  Return 0 on
      success, -1 otherwise.  */
   int (*start_non_stop) (int);
+
+  /* Returns true if the target supports multi-process debugging.  */
+  int (*supports_multi_process) (void);
 };
 
 extern struct target_ops *the_target;
@@ -311,6 +314,10 @@ void set_target_ops (struct target_ops *
 #define target_async(enable) \
   (the_target->async ? (*the_target->async) (enable) : 0)
 
+#define target_supports_multi_process() \
+  (the_target->supports_multi_process ? \
+   (*the_target->supports_multi_process) () : 0)
+
 /* Start non-stop mode, returns 0 on success, -1 on failure.   */
 
 int start_non_stop (int nonstop);
Index: src/gdb/gdbserver/server.c
===================================================================
--- src.orig/gdb/gdbserver/server.c	2009-06-19 14:26:36.000000000 +0100
+++ src/gdb/gdbserver/server.c	2009-06-19 14:34:09.000000000 +0100
@@ -1074,9 +1074,13 @@ handle_query (char *own_buf, int packet_
 	     p != NULL;
 	     p = strtok (NULL, ";"))
 	  {
-	    /* Record if GDB knows about multiprocess support.  */
 	    if (strcmp (p, "multiprocess+") == 0)
-	      multi_process = 1;
+	      {
+		/* GDB supports and wants multi-process support if
+		   possible.  */
+		if (target_supports_multi_process ())
+		  multi_process = 1;
+	      }
 	  }
 
       sprintf (own_buf, "PacketSize=%x;QPassSignals+", PBUFSIZ - 1);
@@ -1106,7 +1110,8 @@ 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_multi_process ())
+	strcat (own_buf, ";multiprocess+");
 
       if (target_supports_non_stop ())
 	strcat (own_buf, ";QNonStop+");
Index: src/gdb/gdbserver/linux-low.c
===================================================================
--- src.orig/gdb/gdbserver/linux-low.c	2009-06-19 14:26:36.000000000 +0100
+++ src/gdb/gdbserver/linux-low.c	2009-06-19 14:34:09.000000000 +0100
@@ -3008,6 +3008,12 @@ linux_start_non_stop (int nonstop)
   return 0;
 }
 
+static int
+linux_supports_multi_process (void)
+{
+  return 1;
+}
+
 static struct target_ops linux_target_ops = {
   linux_create_inferior,
   linux_attach,
@@ -3045,6 +3051,7 @@ static struct target_ops linux_target_op
   linux_supports_non_stop,
   linux_async,
   linux_start_non_stop,
+  linux_supports_multi_process
 };
 
 static void
2009-06-19  Aleksandar Ristovski  <aristovski@qnx.com>
	    Pedro Alves <pedro@codesourcery.com>

	* target.h (struct target_ops) <supports_multi_process>: New
	callback.
	(target_supports_multi_process): New.
	* server.c (handle_query): Even if GDB reports support, only
	enable multi-process if the target also supports it.  Report
	multi-process support only if the target backend supports it.
	* linux-low.c (linux_supports_multi_process): New function.
	(linux_target_ops): Install it as target_supports_multi_process
	callback.

---
 gdb/gdbserver/linux-low.c |    7 +++++++
 gdb/gdbserver/server.c    |   11 ++++++++---
 gdb/gdbserver/target.h    |    7 +++++++
 3 files changed, 22 insertions(+), 3 deletions(-)

Index: src/gdb/gdbserver/target.h
===================================================================
--- src.orig/gdb/gdbserver/target.h	2009-06-19 14:26:36.000000000 +0100
+++ src/gdb/gdbserver/target.h	2009-06-19 14:34:09.000000000 +0100
@@ -275,6 +275,9 @@ struct target_ops
   /* Switch to non-stop (1) or all-stop (0) mode.  Return 0 on
      success, -1 otherwise.  */
   int (*start_non_stop) (int);
+
+  /* Returns true if the target supports multi-process debugging.  */
+  int (*supports_multi_process) (void);
 };
 
 extern struct target_ops *the_target;
@@ -311,6 +314,10 @@ void set_target_ops (struct target_ops *
 #define target_async(enable) \
   (the_target->async ? (*the_target->async) (enable) : 0)
 
+#define target_supports_multi_process() \
+  (the_target->supports_multi_process ? \
+   (*the_target->supports_multi_process) () : 0)
+
 /* Start non-stop mode, returns 0 on success, -1 on failure.   */
 
 int start_non_stop (int nonstop);
Index: src/gdb/gdbserver/server.c
===================================================================
--- src.orig/gdb/gdbserver/server.c	2009-06-19 14:26:36.000000000 +0100
+++ src/gdb/gdbserver/server.c	2009-06-19 14:34:09.000000000 +0100
@@ -1074,9 +1074,13 @@ handle_query (char *own_buf, int packet_
 	     p != NULL;
 	     p = strtok (NULL, ";"))
 	  {
-	    /* Record if GDB knows about multiprocess support.  */
 	    if (strcmp (p, "multiprocess+") == 0)
-	      multi_process = 1;
+	      {
+		/* GDB supports and wants multi-process support if
+		   possible.  */
+		if (target_supports_multi_process ())
+		  multi_process = 1;
+	      }
 	  }
 
       sprintf (own_buf, "PacketSize=%x;QPassSignals+", PBUFSIZ - 1);
@@ -1106,7 +1110,8 @@ 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_multi_process ())
+	strcat (own_buf, ";multiprocess+");
 
       if (target_supports_non_stop ())
 	strcat (own_buf, ";QNonStop+");
Index: src/gdb/gdbserver/linux-low.c
===================================================================
--- src.orig/gdb/gdbserver/linux-low.c	2009-06-19 14:26:36.000000000 +0100
+++ src/gdb/gdbserver/linux-low.c	2009-06-19 14:34:09.000000000 +0100
@@ -3008,6 +3008,12 @@ linux_start_non_stop (int nonstop)
   return 0;
 }
 
+static int
+linux_supports_multi_process (void)
+{
+  return 1;
+}
+
 static struct target_ops linux_target_ops = {
   linux_create_inferior,
   linux_attach,
@@ -3045,6 +3051,7 @@ static struct target_ops linux_target_op
   linux_supports_non_stop,
   linux_async,
   linux_start_non_stop,
+  linux_supports_multi_process
 };
 
 static void