Re: Change stubs to handle '$' after packet start

[Stan Shebs <shebs@cygnus.com>]

   From: jtc@redback.com (J.T. Conklin)
   Date: 19 Aug 1999 20:04:42 -0700

   jtc> This change adds code in getpacket() to start a new packet if
   jtc> the packet start character ('$') is received while reading
   jtc> the packet contents.  This prevents the loss of the
   jtc> subsequent packet if the packet end character '#' is
   jtc> lost/garbled.

   Stan> The change is innocuous, but is it really useful?  

   I think so.  I suspect serial packet protocols which have both begin
   and end packet characters do the same thing.  I checked SL/IP, but
   that only uses a single begin (or end, depending on your point of
   view) character for packet framing.

OK, I buy your argument.  It would be nice to have a place for your
explanation, ideally in the part of the GDB manual that explains how
to write stubs.

   As for letting the user know something is wrong.  Unfortunately, there
   is no good way to indicate to the user that a stub is losing packets.
   We could add a debug_error() call there on those stubs that support
   that function.  We could also add some standard statistics variables
   that could be queried by GDB (number of packets received, number of
   packets sent, number of retries, etc.).  It would be easy enough to
   add the same sorts of counters on the GDB side, which is almost the
   same thing.

That would a useful bit of statistic...

								Stan