SMP TODOs

[klange]

• Resolve remaining race conditions.
  • It seems like some are trashing stacks.
  • We're probably not cleaning up processes sanely between cores: This seems like the area most in need to exploration.
  • The VFS needs a thorough audit!
• Stop spinning idle cores
  • APs should arch_pause(); like the BSP instead of repeatedly checking the
  • We should wake up cores when things enter the ready queue. This needs an IPI that jumps straight to scheduling just like the pre-empt signal, but only if we weren't already running something?
  • We should pre-empt cores with the LAPIC timer. Maybe we can even one-shot it so the cores aren't waking up when truly idle?