13.1 Managing Execution State

A target vector can be completely inactive (not pushed on the target stack), active but not running (pushed, but not connected to a fully manifested inferior), or completely active (pushed, with an accessible inferior). Most targets are only completely inactive or completely active, but some support persistent connections to a target even when the target has exited or not yet started.

For example, connecting to the simulator using target sim does not create a running program. Neither registers nor memory are accessible until run. Similarly, after kill, the program can not continue executing. But in both cases gdb remains connected to the simulator, and target-specific commands are directed to the simulator.

A target which only supports complete activation should push itself onto the stack in its to_open routine (by calling push_target), and unpush itself from the stack in its to_mourn_inferior routine (by calling unpush_target).

A target which supports both partial and complete activation should still call push_target in to_open, but not call unpush_target in to_mourn_inferior. Instead, it should call either target_mark_running or target_mark_exited in its to_open, depending on whether the target is fully active after connection. It should also call target_mark_running any time the inferior becomes fully active (e.g. in to_create_inferior and to_attach), and target_mark_exited when the inferior becomes inactive (in to_mourn_inferior). The target should also make sure to call target_mourn_inferior from its to_kill, to return the target to inactive state.