(gdb) thread target [id] : allows the user to get/set the target thread.
The argument id is either the thread's symbolic name or its local identifier.
(gdb) thread detach [id...] : all stops (breakpoints) of some specified
thread(s) can be ignored using the thread detach command. Each time a detached
thread hits a breakpoint, RTEMS/GDB will automatically restart the debuggee
without passing control to the user.
RTEMS/GDB User's Guide