Re: GDB/MI

Andrew Cagney
2003-02-21T01:45:06Z

> The debugger mode that uses GDB/MI which I am trying to write for Emacs uses a
> queue but I can't get it initialised properly. This is why:
>
> If I start with gdb -interp=mi mytest, I get
>
> ~"GNU gdb 2003-02-04-cvs\n"
> ~"Copyright 2003 Free Software Foundation, Inc.\n"
> ~"GDB is free software, covered by the GNU General Public License, and you are\n"
> ~"welcome to change it and/or distribute copies of it under certain conditions.\n"
> ~"Type \"show copying\" to see the conditions.\n"
> ~"There is absolutely no warranty for GDB. Type \"show warranty\" for details.\n"
> ~"This GDB was configured as \"i586-pc-linux-gnu\"..."
> ~"\n"
> (gdb)

The prompt:

"(gdb)\n"

indicates that GDB is ready for input. That prompt terminates every
transaction. It is independant of the console GDB prompt:

(gdb)
-interpreter-exec console set prompt foo
&"Argument required (expression to compute).\n"
^error,msg="Argument required (expression to compute)."
(gdb)
-interpreter-exec console "set prompt foo"
^done
(gdb)
-interpreter-exec console "show prompt"
~"Gdb's prompt is \"foo\".\n"
^done
(gdb)

There is a `bug' here - GDB should generate a `=prompt-changed' event.

Andrew

> ^Z^Zpre-prompt
> (gdb)
> ^Z^Zprompt
>
> and the prompt annotation tells Emacs that GDB is ready for input. Since Emacs'
> interaction is asynchronous, the timing is wrong if I assume GDB is ready for
> input immediately after its invocation. I think the initial output should be:
>
> ~"GNU gdb 2003-02-04-cvs\n"
> ~"Copyright 2003 Free Software Foundation, Inc.\n"
> ~"GDB is free software, covered by the GNU General Public License, and you are\n"
> ~"welcome to change it and/or distribute copies of it under certain conditions.\n"
> ~"Type \"show copying\" to see the conditions.\n"
> ~"There is absolutely no warranty for GDB. Type \"show warranty\" for details.\n"
> ~"This GDB was configured as \"i586-pc-linux-gnu\"..."
> ~"\n"
> ^done
> (gdb)
>
> i.e GDB should notify its status with the ^done record.
>
> I could look for the prompt (gdb) for notification and I imagine this is what
> gvd does but the idea presumably is to have a machine interface and not rely
> on output intended for the (human) user. For example this could be defeated
> with `set prompt'.
>
> I will file a bug report if someone agrees with my analysis.
>
> Nick
>
> Incidently, the string (gdb) that is output here is not the prompt but an
> imposter as I get:
>
> -gdb-set prompt (hec)
> ^done
> (gdb)
> -gdb-show prompt
> ^done,value="(hec)"
> (gdb)
>