In GDB's all-stop mode, whenever your program stops, all
execution threads stop. Likewise, whenever you restart the
program, all threads start executing. See All-Stop Mode. For
some multi-threaded targets, GDB supports a further mode of
operation, called non-stop mode, in which you can examine
stopped program threads in the debugger while other threads
continue to execute freely. See Non-Stop Mode. Versions of GDB
prior to 7.0 do not support non-stop mode, and it does not work
on all targets. gdb-non-stop-setting determines whether Emacs
runs GDB in all-stop mode or non-stop mode. The default is which
means it tries to use non-stop mode if that is available. If you
change the value to nil, or if non-stop mode is unavailable,
Emacs runs GDB in all-stop mode. The variable takes effect when
Emacs begins a debugging session; if you change its value, you
should restart any active debugging session. When a thread stops
in non-stop mode, Emacs usually switches to that thread. If you
don't want Emacs to do this switc