On Sat, Jul 12, 2008 at 08:21:49PM +0400, Oleg Nesterov wrote:
Sorry for the delay... I'm a bit tied down to other things until aug
I tried this on a Power system sometime back and I was able to
offline CPU0. What I am not sure however, is
if that was the boot-cpu.
On x86, I do remember reading somewhere why we cannot offline
Yes, in arch/x86/kernel/topology.c
int __ref arch_register_cpu(int num)
* CPU0 cannot be offlined due to several
* restrictions and assumptions in kernel. This basically
* doesnt add a control file, one cannot attempt to offline
* Also certain PCI quirks require not to enable hotplug control
* for all CPU's.
per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
Not very sure about this one.
Thanks and Regards