Re: MI non-stop mode spec

[Daniel Jacobowitz <drow@false.org>]

On Fri, Mar 21, 2008 at 11:12:34AM -0700, Pawel Piech wrote:
> The Wind River debugger which implements the MI protocol, supprots  
> multi-core/multi-process debugging, non-stop and all-stop debugging modes 
> simultaneously (for different targets), uses the above protocol  
> extensions for several years now rather successfully.  So I hope you  
> consider these suggestions seriously even if they are not easiest to  
> implement given the GDB architecture.

Hi Pawel,

Is there any documentation for Wind River's MI protocol which you
could share with us as a basis?  Either with the list, or privately
with CodeSourcery - we have some NDAs in place with Wind River, if
that's needed.  Obviously you have some implementation experience
that we'd love to benefit from here.

Multi-core, multi-process, and multi-thread debugging are all
different but they're very tightly related so thinking about them
all at once may be best.  GDB's only current support for multi-core
models each core as a thread; in some cases that's exactly right,
in some it isn't.

Though perhaps we should break that out into a separate conversation.
The current threading model is enough to make hopefully solid progress
on non-stop for a single multi-threaded program.

I think the most attractive option I've seen so far is to make
automatic context switching optional.  We could disable it by default
when non-stop debugging is enabled.  Or a smarter version:
automatically switch contexts when we stop if previously selected
thread was running.  So if all threads are running and one thread gets
an event, we will automatically switch to that thread; but if two
threads stop in quick succession we'll leave the first one selected.
That might be overly confusing for MI clients; I'm thinking about
a hypothetical CLI version here.

-- 
Daniel Jacobowitz
CodeSourcery