Re: Is "QTBuffer:size" a packet, or "QTBuffer:" plus an argument?

[Pedro Alves <palves at redhat dot com>]

On 02/17/2012 07:49 AM, Yao Qi wrote:
> On 02/16/2012 01:22 AM, Pedro Alves wrote:
>> One question this raises is, is the right response to
>> QTBuffer:size:ffffffff, "E01", or an empty reply, indicating packet
>> not supported?  IOW, are QTBuffer:size and QTBuffer:circular two
>> different packets, or a single QTBuffer: packet with different
>> arguments?  This makes a difference if GDB is to gracefully detect
>> when the target side doesn't support QTBuffer:foo.
> 
> IMO, "QTBuffer" is the packet, and "size" is an argument.  

> I hope the right response to QTBuffer:size:ffffffff is an empty reply, means 
> remote stubs don't support QTBuffer:size.  Reply "E01" means remote stub
> supports QTBuffer:size, but unable to meet this request, due to some
> reasons, limited memory, for example.

Thing is empty reply implies it's a different packet, so we can't
have both.  I also think the right answer is empty reply.  I realized
we also consider the qXfer:$obj:read different packets, so there's
precedent for thinking of `:' as part of the packet.  BTW, the packet
is documented as:

 @item QTBuffer:circular:@var{value}
 This packet directs the target to use a circular trace buffer if
 @var{value} is 1, or a linear buffer if the value is 0.

So I don't think anything needs to change there.

So here's the patch I propose to check in.

2012-02-20  Pedro Alves  <palves@redhat.com>

	* tracepoint.c (cmd_bigqtbuffer): Rename as ...
	(cmd_bigqtbuffer_circular): ... this.  Only handle
	'QTBuffer:circular:'.
	(handle_tracepoint_general_set): Adjust.

---

 gdb/gdbserver/tracepoint.c |   24 +++++++++---------------
 1 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/gdb/gdbserver/tracepoint.c b/gdb/gdbserver/tracepoint.c
index 5c565fe..cd58c2d 100644
--- a/gdb/gdbserver/tracepoint.c
+++ b/gdb/gdbserver/tracepoint.c
@@ -3794,24 +3794,18 @@ cmd_qtbuffer (char *own_buf)
 }

 static void
-cmd_bigqtbuffer (char *own_buf)
+cmd_bigqtbuffer_circular (char *own_buf)
 {
   ULONGEST val;
   char *packet = own_buf;

-  packet += strlen ("QTBuffer:");
+  packet += strlen ("QTBuffer:circular:");

-  if (strncmp ("circular:", packet, strlen ("circular:")) == 0)
-    {
-      packet += strlen ("circular:");
-      unpack_varlen_hex (packet, &val);
-      circular_trace_buffer = val;
-      trace_debug ("Trace buffer is now %s",
-		   circular_trace_buffer ? "circular" : "linear");
-      write_ok (own_buf);
-    }
-  else
-    write_enn (own_buf);
+  unpack_varlen_hex (packet, &val);
+  circular_trace_buffer = val;
+  trace_debug ("Trace buffer is now %s",
+	       circular_trace_buffer ? "circular" : "linear");
+  write_ok (own_buf);
 }

 static void
@@ -3930,9 +3924,9 @@ handle_tracepoint_general_set (char *packet)
       cmd_qtframe (packet);
       return 1;
     }
-  else if (strncmp ("QTBuffer:", packet, strlen ("QTBuffer:")) == 0)
+  else if (strncmp ("QTBuffer:circular:", packet, strlen ("QTBuffer:circular:")) == 0)
     {
-      cmd_bigqtbuffer (packet);
+      cmd_bigqtbuffer_circular (packet);
       return 1;
     }
   else if (strncmp ("QTNotes:", packet, strlen ("QTNotes:")) == 0)