[Bug 183720] acpi should be enabled by default for kvm guest

[fishor]

Public bug reported:

ubuntu as kvm guest couse more wakeups if it started without acpi.
Normally kernel will try to find aout the date of the BIOS and bcouse
kvm/qemu do not have DMI table it will fault and force start without
acpi.

Results of powertop:

kvm guest with acpi forced
Wakeups-from-idle per second : 107,1    interval: 15,0s
Top causes for wakeups:
  55,2% ( 68,5)   qemu-system-x86 : sys_timer_settime (posix_timer_fn)
   8,2% ( 10,2)   qemu-system-x86 : start_apic_timer (apic_timer_fn)

kvm guest without acpi
Wakeups-from-idle per second : 191,4    interval: 15,0s
Top causes for wakeups:
  54,4% (168,3)   qemu-system-x86 : sys_timer_settime (posix_timer_fn)
  32,3% (100,0)   qemu-system-x86 : __kvm_migrate_apic_timer (apic_timer_fn)

** Affects: linux-meta (Ubuntu)
     Importance: Undecided
         Status: New

-- 
acpi should be enabled by default for kvm guest
https://bugs.launchpad.net/bugs/183720
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