Re: MP development needs

["Simon 'corecode' Schubert" <corecode@xxxxxxxxxxxx>]

Matthew Dillon wrote:
> :Hey,
> :
> :I just wanted to drop this as a note so that I won't forget about it and maybe some (masochistic) people want to pick up these as a task.
> :
> :For sensible MP development, we need:
> :
> :- a core dump format which will reflect lwps
> :- a GDB which can handle lwps
> :- best a KGDB which works with vkernels/threads
> :- a working kernel profiler (pmc, oprofile, at least working gprof, dtrace?)
> :
> :did I forget something?  as ususal, feedback expected.
> :
> :cheers
> :  simon
>
>     This main issue here is for someone to research how GDB handles
>     threading and to then device a kernel API (e.g. via /proc that gdb
>     can tie into directly).  The core dump format would be pretty straight
>     forward.

No, gdb uses ptrace.  So we need to change the ptrace API to be able to specify the tid as well, not just the pid.  Linux doesn't need this, because they have a pid per thread.  We'd have to check what freebsd and netbsd are doing.

>     Right now the register state is stored in the core dump via an ELF note
>     in the elf_corehdr() and elf_puthdr() procedures.  Basically we would
>     want to add an ELF note for each thread that we can then parse back out
>     in GDB.

exactly.  just has to be done.  dito for checkpointing, btw.

cheers
 simon

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