Syscall API: thread creation

• Previously, threads were created using a function:

  rfork_thread(int flags, void *stack_ptr, void (*func)(void *), void *arg)

  1. called rfork(flags)

  2. change stack register to stack_ptr

  3. invoke func(arg)

• what happens if the new thread receives a signal between (1) and (2)?

  • new thread uses the parent thread's stack while processesing the signal!

  • "Boom"