GDB/MI

Nick Roberts
2003-02-21T01:20:14Z

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)

I see that the text is now escaped with ~ so I know this is output for the
console. However, Emacs don't know that GDB is ready for input. With level 2
annotations, I get:

GNU gdb 2003-02-04-cvs
Copyright 2003 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "i586-pc-linux-gnu"...
breakpoints-invalid

^Z^Zframes-invalid

^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)