Speaker Zachary Amsden; Jeremy Fitzhardinge; Rusty Russell, IBM; Chris Wright, Redhat
Time 2007-01-19 14:00
Conference LCA2007

All the cool kids are doing it!

Zachary Amsden
Jeremy Fitzhardinge
Rusty Russell, IBM
Chris Wright, Redhat

Shadow page tables

  • twice as much memory
  • two copies page tables
  • changes by guest erquire trapping hypervisor

or alternative:

  • security
  • I/O - emulate
  • create simplified drivers


  • identify CPU features
  • not trappable
  • not a privileged instruction

popf, pushf

  • kernel can’t run except in ring 0



  • rewrite code in kernel not to use problem instructions
  • Xen

Xen interrupts

  • GPL hypervisor
  • IDT interrupt descriptor table
  • virtual IRQs


  • cute cuddly lawyer
  • one kernel can run anywhere
  • different OS run on different hypervisors without making code changes
  • published by hypervisor
  • called by kernel



lguest - rusty visor

virtbench - VT

KVM hypervisor

can you run a hypervisor under a hypervisor?

standard video card, etC?

we should fix the OS, but it isn’t as cool.