[MI] -break-insert: (a)synchronous?

Keith Seitz keiths@redhat.com
Thu Jun 13 19:27:00 GMT 2002


On Thu, 13 Jun 2002, Andrew Cagney wrote:

> The command was implemented that way to match its documented spec.  I
> remember wondering about alternate implementations at the time.
>
> Sounds like it is time to either define a new command (not capture the
> events) or change the spec.

Ok, then I would like to propose that we change the spec to use events and
only events when a command results in some event. This reduces the
redundancy.

I'm working on modifying gdbmi.texinfo, but I am a little confused about
all the stream options:

"*" = "exec-async-output"
"+" = "status-async-output"
"=" = "notify-async-output"

>From the manual ([] = my comments):
  o status-async-output contains on-going status information about the
    progess of slow operation. All status output is prefixed by "+".
    [I presume that the biggest client for this is downloading to a target.]
  o exec-async-output contains asynchronous state change on the target
    (stopped, started, disappeared). All Async output is prefixed by "*".
    [This seems to be called only by async target state changes.]
  o notify-async-output contains supplementary information that the client
    should handle (e.g., a new breakpoint information). All notify
    output is prefixed by "=".
    [I don't know where this is used. I am unable to find any references
     to this.]

>From the descriptions above, it sounds like event notifications should
occur on the notify-async-output channel, "=".

However, if one reads down to the "Command With Side Effects" section, one
sees:

-> -symbol-file xyz.exe
<- *breakpoint,nr="3",address="0x123",source="a.c:123"
<- (gdb)

The exact meaning of this example is not really clear to me, but I
presume that it is meant to demonstrate what happens when a breakpoint is
inserted as a result of loading a new symbol file (however that may
occur). In any case, the example is certainly not exec-async-output. In
fact, it is nothing in the MI lingo.

To get the ball rolling on cleaning some of this up, I will submit a patch
which changes (replaces?) the meaning of notify-async-output to include
events in the debugger (breakpoints inserted/deleted/modified,
architecture changes, stack frame changes, switching current thread, etc),
and I will update all the examples.

If someone reads this differently than I do, please speak up.

So, here's how I interpret what should happen:

(gdb)
-break-insert main
=breakpoint-create,number="1"
^done,bkpt=...
(gdb)

(I will also be proposing that we whack the result in this case, since we
will get an event notification, too.)

Keith





More information about the Gdb mailing list