I've had a use for this more than once, but I never had it
in GDB proper --- always had to patch it first.  Sometimes, I'd
like to be able to easily ask a client to give us remote protocol
timestamps, to help diagnose timing issues on stubs we don't
have easy access to --- missing TCP_NODELAY, unwanted buffering,
really slow flash writing, etc., in such cases you'll easily
spot unusual > ms delays somewhere.

I'm making use of this:

 /* Debugging level.  0 is off, and non-zero values mean to print some debug
    information (higher values, more information).  */
 extern int remote_debug;

... to enable timestamps, you do "set debug remote 2".  level 1
still outputs the same as usual.

With acks:

 1226687336.526: Sending packet: $Xf7efde30,1:U#d8...
 1226687336.526: Ack

 1226687336.526: Packet received: OK

 1226687336.526: Sending packet: $X80484d5,1:�#57...
 1226687336.526: Ack

In no-ack mode (e.g., against current gdbserver):

 1226687726.796: Sending packet: $Xf7fdfe30,1:U#d9...
 1226687726.796: Packet received: OK

 1226687726.806: Sending packet: $X80484d5,1:�#57...
 1226687726.806: Packet received: OK

WDYT?

-- 
Pedro Alves