pub fn env_alloc(parent_id: u32) -> Result<usize, KError>Expand description
Alloc an env and setup its vm and PCB.
§Return
If there is at least one free env, and the env_setup_vm works well, the
raw pointer to the new env will be returned with a Ok wrapper.
Otherwise, a KError with a Err wrapper will be returned if there is no
free env (KError::NoFreeEnv) or env_setup_vm fails.
§Safety
The env got in the free list SHALL be valid.