[systemd-devel] [PATCH] Add the CPU hotplug rule

[John Haxby]

On 02/09/14 16:40, Kay Sievers wrote:
>>> >> But just in case someone thinks of any per-CPU onlining policy
>>> >> machinery now: We will not ship anything in that area in systemd/udev
>>> >> upstream. This stuff just belongs into the kernel, like it works for
>>> >> any other device.
>> >
>> > Do you mean that the kernel should not be generating udev events for cpu
>> > hotplug?
> Sure, nothing wrong with these events.
> 
>> > Or that there is some other mechanism that the kernel should
>> > be using to allow cpu hotplug policy to be decided by userland?
> It should not be decided by userland. And as the proposed rules show,
> nobody needed that so far, and we are not making up theoretical use
> cases here now, just as an argument for the userspace even echo.
> 
> If things should be onlined when they show up, the kernel should just
> do that itself. There is no point in looping anything like that by
> default through userspace. It is the same as automatic driver-binding,
> it can (nobody does that) be disabled and taken-over by userspace, but
> the default is just in the kernel where it belongs.


Hmmm.   I wonder why the kernel policy is not to put the cpu online?  I
know it's been that way for some time now which is why we had the old
"bring it online" udev rule.

I'll go hunting.

jch