user_regset_active_fn —
type of active function in struct user_regset
typedef int user_regset_active_fn ( | struct task_struct * target, |
const struct user_regset * regset); |
Return -ENODEV if not available on the hardware found.
Return 0 if no interesting state in this thread.
Return >0 number of size units of interesting state.
Any get call fetching state beyond that number will
see the default initialization state for this data,
so a caller that knows what the default state is need
not copy it all out.
This call is optional; the pointer is NULL if there
is no inexpensive check to yield a value < n.