Considering that I'm not familiar with SWD, and there's not much time left before hackathon, I will start with GDB stub over serial, providing a very limited scope of features, namely registers info and stack dumping. Backtrace may be available as well, but before it is committed I have to go over ARM arch, which I haven't played for a couple of years. I can use my own mbed-M0 with breadboard to code some prototype. BTW, I have a feeling that a sophisticated GDB-over-serial is able to provide all functions that SWD can provide. Is that correct? On Wed, May 14, 2014 at 10:27 AM, Pekka Nikander <pekka.nikander@xxxxxx>wrote: > > Yes the gdb remote protocol is the best option. Either over serial or > over SWD is fine for me, though I know few about SWD. But I don't get why > we need a Blackmagic. All we need are a serial cable and whatever gdb > frontend, right? > > SWD has hardware support, so it makes it possible to trace execution, stop > it, etc. Hence, if we have something like blackmagic that speaks SWD > directly to our board, and connect it with GBD using the GDB remote, then > we would have full debugging capability. > > OTOH, having a minimal GDB stup speaking directly serial would also be > very useful, as it would allow to do "core dumps", i.e. figure out what > went wrong, even when SWD might not be available. > > Still another, different idea might be to write a minimal TFTP server that > would serve the whole memory contents in the case of a crash, allowing one > to slurp the memory contents after a crash. > > --Pekka > >