linux native async mode support

[Nick Roberts]

 > > There's an extra "^done" because this is a CLI command entered in MI (and
 > > therfore case CLI_COMMAND: of captured_mi_execute_command).  There are many
 > > issues here like should we diallow immediate use of CLI commands now and
 > > require explicit use of "-interpreter-exec console"?
 > 
 > Probably not -- I don't see any immediate advantage from that.

The node "GDB/MI Compatibility with CLI" explains why.

 > > Then "-interpreter-exec 
 > > console next" doesn't emit "(gdb)/n" after "^running" when in asynchronous
 > > mode, so should we remove it from synchronous mode too (as you have suggested)?
 > 
 > This prompting is fairly confusing, so it could be that I've confused myself
 > as well, but I think "-interpreter-exec console next" actually *should* print
 > the prompt if the target is async-capable. The reason is that for MI mode,
 > we don't really care about terminal ownership issues, and then should not
 > care about sync_execution, and then this bit of code:
 > 
 >       else if (sync_execution)
 > 	{
 > 	  /* Don't print the prompt. We are executing the target in
 > 	     synchronous mode.  */
 > 	  args->action = EXECUTE_COMMAND_SUPPRESS_PROMPT;
 > 	  return;
 > 	}
 > 
 > in captured_mi_execute_command should be removed. In fact, I have a
 > patch-in-progress to do exactly that, and hopefully will be posting it later
 > today.

OK.

 > > But these are all MI issues and this test is meant to just be a mark in the
 > > sand for asynchronous mode, and one that I had lying around.  For the moment, I
 > > don't really want to work on it further
 > 
 > Okay :-) Then, will you mind if I apply this patch either when I'm done with
 > another round of MI testsuite cleanups I'm doing today, or after the ^done
 > is gone, whichever proves more convenient?

I'll commit this as is then.  Then, of course, you can decide what changes you
wish to make.  Meanwhile I'll try to come up with some tests for floating
variable objects which will be more efficient use of my time.


 > >  > BTW, I'm not even sure that "^done" vs. "^running" + "^done" is so big
 > >  > difference that a helper function cannot be introduced.
 > > 
 > > The comment suggests that mi_gdb_test will not work but I have not revisited
 > > that since writing the test 18 months or so ago.  If true, that could also
 > > make helper functions difficult.
 > 
 > Do you happen to remember what race condition the comment mentions?

I must have copied the comment from mi-simplerun.exp and I think I found it
necessary with my asynchronous branch, although I can't be sure, and it may
not be be necessary with Pedro's version (.i.e. mainline).

-- 
Nick                                           http://www.inet.net.nz/~nickrob