lab-5-file-system-spawn-and-shell.md

Lab 5: File system, Spawn and Shell

Question

1. Do you have to do anything else to ensure that this I/O privilege setting is saved and restored properly when you subsequently switch from one environment to another? Why?

   Processor pushed eflags value to kernel stack at trap, the register will be restored by iret when kernel try to rerun the environment.

2. Think about what you would have to do in order to implement exec in user space, and be sure you understand why it is harder.

   Program exec need to replace image and setup frame while itself is running.