Unsupported X packets (write binary data)

[daniel5151]

Unsupported X packets (write binary data)

[daniel5151]

Yep, gdbstub doesn't currently implement X, since AFAIK, the GDB client simply falls back to using the M packet to write data to memory if X is not implemented. The M packet uses a less efficient ASCII hex representation of data, though it seems that no one had noticed or cared enough to implement the more efficient X packet.

Thankfully, this packet seems to be solely an "optimization" packet, and won't require a new user-facing API. It would use the existing Target::write_addrs APIs, just like the M packet.

I'd be more than happy to merge an implementation of X packet handling. The implementation ought to be quite straightforward, since it would be almost an exact copy of the current M packet handling code, albeit with decode_hex_buf swapped out for decode_binary_buf in the packet parsing code.

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Also, sidenote: that example packet you gave seems a bit weird 👀
Why would GDB waste bandwidth trying to write data with a length of zero?

Fascinating...

[gz]

Yea not sure about that zero length packet. There are still some bugs in my implementation with stepping, either just getting stuck or reporting some errors like Protocol error: P (set-register) conflicting enabled responses. when I turn on single register writes. So can't tell yet if I broke something horribly or if it's really gdb doing that.