Allow GDB connection

[nedv-eu]

I was wondering whether it will be possible to include gdb-server stub from probe-rs to probe-run. The idea is to allow GDB connection and use regular debugging while maintain display of defmt log messages.

When the probe-run is running it is not possible to access the st-link probe from the gdb-server nor OpenOCD. So to allow this to work a GDB session has to be somehow integrated into the probe-run.

[jonas-schievink]

The idea is to allow GDB connection and use regular debugging while maintain display of defmt log messages.

I think probe-rs currently does not support multiplexing the connection like that, but this would indeed be nice to have!

[nedv-eu]

I started thinking about alternative defmt host that will use openocd as it's backend. I will try to hack together a proof of concept in next few days. So far I proved I can control target using telnet interface when a gdb session is active.

[japaric]

update: tried the git version of cargo-embed today and it supports RTT and GDB server running concurrently so presumably this should be supported in the git version of probe-rs. cargo-embed 0.10.1 does not support the concurrent connection.

[japaric]

PR #315 is a PoC GDB server for postmortem debugging

[rursprung]

update: tried the git version of cargo-embed today and it supports RTT and GDB server running concurrently so presumably this should be supported in the git version of probe-rs. cargo-embed 0.10.1 does not support the concurrent connection.

this feature had been released in june 2021 with cargo-embed 0.11.0, see their blog post and the underlying support must accordingly be in a released version of probe-rs.
it'd be great if it'd be possible to use probe-run with GDB and defmt-rtt in parallel - or at least with GDB (defmt-rtt could maybe be disabled during that time as the messages can be seen when stepping through with the debugger?)