_lwp_makecontext() initializes the context structure pointed to by
context in a manner suitable for using with
_lwp_create(2). The LWP will begin execution at the function specified by
start_routine which will be passed a single argument
arg. The LWP private data pointer will be set to
private. The stack region for the new LWP is specified by the
stack_base and
stack_size arguments.
The signal mask in the context structure is not initialized by
_lwp_makecontext().