Re: [RFC 0/2, gdbserver] Set linux target in async mode in default

[Yao Qi <yao at codesourcery dot com>]

On 09/26/2012 12:23 AM, Pedro Alves wrote:
> Please explain better why this is necessary (probably with an example).
> What exactly doesn't work if you don't do this change?  It sounds as though

Hi, Pedro,
When we have a notification, we'll queue it and call 'async_file_mark'. 
 Then, notification can be sent in async handler 'handle_target_event' 
later, which is done by my later patch posted here, mainly in 
server.c:handle_target_event,

   [PATCH 3/6] de-couple %Stop from notification: gdbserver
   http://sourceware.org/ml/gdb-patches/2012-09/msg00480.html

The whole process is identical to all notifications, including %Stop. 
Actually, this process is generalized from %Stop.

For example, we need a notification on 'trace status', and GDBserver 
will send it once trace is stopped due to some reasons, such as 
tracebuffer is full.  We can add some code below to trigger event-loop, 
so that such notification can be sent later (it doesn't compile, just to 
show why do we need async for sending notification).

diff --git a/gdb/gdbserver/tracepoint.c b/gdb/gdbserver/tracepoint.c
index 201a25b..1135f53 100644
--- a/gdb/gdbserver/tracepoint.c
+++ b/gdb/gdbserver/tracepoint.c
@@ -3472,6 +3472,10 @@ stop_tracing (void)
     }

   unpause_all (1);
+
+#ifndef IN_PROCESS_AGENT
+  QUEUE_enque (notif_p, notif_queue, &notif_trace);
+  async_file_mark ();
+#endif
 }

 static int

Otherwise, when/how should we send notification in GDBserver?

> this could make gdbserver push notifications down to GDB in all-stop
> mode even when it isn't waiting for server replies?

I am assuming that 'it' means GDB', so answer is 'yes'.

If I understand 'non-stop for remote target' stuff correctly, %Stop 
notification is sent to GDB in non-stop mode even when GDB isn't waiting 
for server replies.  Then, what I am trying to achieve is 'notifications 
are sent to GDB in all-stop or non-stop mode even when GDB isn't waiting 
for server replies'.


--
Yao