Finish GDB support for PRU

[dinuxbg]

Explore GDB PRU port feasibility. So far there is a very rough GDB backend for the PRU simulator target.

The following items remain to be implemented:

• Stack unwiding support. This is needed for source-level GDB debugging.
• Real target backend support via remoteproc framework, preferably without an intermediate gdbserver.

[EphDoering]

What's the status of this? I saw some news that GDB 9 has PRU emulator support, but haven't found much else about it.

[dinuxbg]

Yes, GNU Simulator has been ported to PRU. I use it to run the GCC regression testsuite on the PRU backend. You can also use it for simulation - see this example.

FYI, GNU simulator supports tracing:

$ pru-run --trace --trace-insn --trace-disasm --trace-core out/pru-core.elf
...
read-4 exec:0x200004f4 -> 0x0120e2e2
memory:   read of insn 0x0120e2e2 from 200004f4
disasm:   add	sp, sp, 32
...

I tried to port GDB but never got the time to finish it. Feel free to take over.