Re: [PATCH] gdbstub: only send stop-reply upon request

[Peter Maydell]

On Tue, 23 Aug 2022 at 16:07, Matheus Tavares Bernardino
<quic_mathbern@quicinc.com> wrote:
>
> The GDB remote serial protocol[1] specifies that the communication
> between GDB and the stub is driven by GDB:
>
>     The host (GDB) sends commands, and the target (the debugging
>     stub incorporated in your program) sends a response.
>
> This is further emphasized by Embecosm's "Howto: GDB Remote Serial
> Protocol" document[2], which says:
>
>     This is the only circumstance under which the server sends a
>     packet: in reply to a packet from the client requiring a
>     response.

That document is 14 years old and is not a reliable reference
for the protocol today...

In particular,
https://sourceware.org/gdb/download/onlinedocs/gdb/Notification-Packets.html
says:
"The GDB remote serial protocol includes notifications, packets that
require no acknowledgment. Both the GDB and the stub may send
notifications (although the only notifications defined at present
are sent by the stub)."

That said, the thing we're sending here isn't a notification, so
it's not like we're in compliance with the protocol. So I guess
I'm just saying the commit message could be improved.

(The notification mechanism does allow notification of "we just
stopped" if the stub implements non-stop mode, but we don't and
it would be a real pain to try, so that's a bit of a red herring.)

thanks
-- PMM