GDB on a DECstation 3100

[Per Bothner]

I have been playing with getting gdb to run on the 3100.
I have made quite a bit of progress, but there are non-trivial
problems outstanding. [There are also legal issues to deal with.]

The DECstation complicates life for gdb quite a bit.
The main problem is the one-of-a-kind symbol-table format,
which is rather complicated. The other main difficulty is that
it is a RISC machine, with very lean procedure calling conventions.
E.g., there is no dedicated Frame Pointer, so you need information
from the symbol table to do a stack trace. Also, I am missing sme
documentation.

I have working:
- Assembler-level ("misc") symbols.
- Reading memory and registers.
- Stack trace.
- Running programs.

Main known problems that remain:
- Line number information. (I'm still confused about the format of
the line number table.)
- Reading other symbol information. (Reading type information
looks to be the most work.)
- Dis-assembler.
- Subroutine call.
- Core files (should be easy).

I don't know how much more progress I'll be able to make,
but if you can help, get in touch with me.

-- 
	--Per Bothner
Western Software Lab, Digital Equipment, 181 Lytton Ave, Palo Alto CA 94301
bothner at wsl.dec.com ...!decwrl!bothner