bitkeeper revision 1.1389.4.1 (42778db0fg1Gd_OZr6N8_onX23xy3g)

bitkeeper revision 1.1389.4.1 (42778db0fg1Gd_OZr6N8_onX23xy3g)

Patch to allow vcpu hotplugging in domU
Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
From: Ryan Harper
  Two config changes are required to use this change:
    1) CONFIG_SMP=y
    2) CONFIG_HOTPLUG_CPU=y

  I've tested unplugging/plugging cpus in domU via the sysfs interface
  that the patch provides.

  hungerforce:~# grep processor /proc/cpuinfo
  processor       : 0
  processor       : 1
  processor       : 2
  processor       : 3
  hungerforce:~# cd /sys/devices/system/cpu/
  hungerforce:/sys/devices/system/cpu# echo 0 > cpu3/online
  hungerforce:/sys/devices/system/cpu# grep processor /proc/cpuinfo
  processor       : 0
  processor       : 1
  processor       : 2
  hungerforce:/sys/devices/system/cpu# echo 1 > cpu3/online
  hungerforce:/sys/devices/system/cpu# grep processor /proc/cpuinfo
  processor       : 0
  processor       : 1
  processor       : 2
  processor       : 3

  It seems that all processors besides cpu0 can be removed.  I've not done
  any investigation nor optimization of the hotplug patch.  I attempted to
  unplug cpus in dom0, but this resulted in Xen rebooting.

Makefile, Kconfig, smpboot.c, smp.c, process.c, irq.c:
  Fix hotplug cpu support.
Makefile:
  Setup reach-over build of topology.o.
i386-cpu-hotplug-updated-for-mm.patch:
  Add i386 hotplug patch from:
  ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.11-rc5/2.6.11-rc5-mm1/broken-out/i386-cpu-hotplug-updated-for-mm.patch
i386-cpu-hotplug-updated-for-mm.patch, Makefile:
  new file
traps.c, smpboot.c, smp.c, process.c, irq.c, Kconfig:
  Merge changes from hotplug patch.