Re: Inquiry: Should we remove "isolcpus= kernel boot option? (mayhave realtime uses)

[Max Krasnyansky]

Ingo Oeser wrote:
> Hi Max,
> 
> On Wednesday 04 June 2008, Max Krasnyanskiy wrote:
>> btw Ingo, I just realized that maxcpu= option is exactly what you need.
>> Here is how you can use it.
>> Boot your system with maxcpus=1. That way the kernel will only bring up 
>> processor 0. I'm assuming cpu0 is "good" otherwise your system is totally 
>> busted :). Other cpus will stay off-line and will not be initialized.
>> Then once the system boots you can selectively bring "good" processors online 
>> by doing
>> 	echo 1 > /sys/devices/system/cpu/cpuN/online
>>
> 
> I just tested it on the Ubuntu Hardy standard kernel on an AMD DualCore.
> The /sys/devices/system/cpu/cpu1 entry doesn't show up.
> 
> I can send you the dmesg/config in private, if you want.
> 
> Did you test your suggestion? 
No, I just give random suggestions without verifying them first ;-).
Of course I tried it. Sounds like your Ubuntu kernel does not have "CPU
hotplug / suspend on SMP" enabled. I thought that all distributions enable it
by default these days.

Max
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