updated: 2022-01-23_12:32:31-05:00

created: 2021-10-22T08:02:22-04:00
updated: 2021-10-22T08:02:22-04:00

Limited Direct Execution

What to limit?

  • General memory access

  • I/O

  • Special x86 instructions like lidt
    how? get hw help but processes in 'user mode'

  • Smooth context switching makes each process think it has its own CPU (Virtualization)

  • Direct execution makes processes fast

  • HW provides a lot of OS support

    • limited direct execution
    • timer interrupts
    • automatic register saving