[PATCH 3/3] gdb, gdbserver: introduce the 'x' RSP packet for binary memory read

[Tom Tromey]

>>>>> Aktemur, Tankut Baris <tankut.baris.aktemur@intel.com> writes:

> Probing needs to sends an address: Which address shall we use? The same address we
> are given in the first encounter?  And the length is 0.  Then, what if the address
> is bad, e.g.  in an inaccessible region?  But because the length is 0, should the target
> send a success result or an error?  From GDB's PoV, for probing, it doesn't matter, but 
> from target's perspective, I think it creates an odd situation.

I think the probing idea is that you simply try the 'x' command the
first time it is needed.  If remote sends an empty response (not an 'E'
response), then the packet isn't supported, so you disable it and retry
with 'm'.

This is documented in the Overview node:

       For any COMMAND not supported by the stub, an empty response (‘$#00’)
    should be returned.  That way it is possible to extend the protocol.  A
    newer GDB can tell if a packet is supported based on that response.

Tom