Re: [PATCH] x86, smpboot: allow manual hotplug of CPUs

From: H. Peter Anvin
Date: Wed Nov 21 2012 - 13:38:02 EST


On 11/21/2012 10:35 AM, Sasha Levin wrote:
>>
>> Reading between the lines, this sounds like would cause a user-visible
>> difference between mptable platforms and ACPI platforms? If so, that is
>> totally unacceptable. If not, the description is confusing.
>
> With ACPI platforms you don't need probe/release because the hardware notifies
> on CPU insert/eject - this doesn't exist on mptable which is why you have to
> do it manually with probe/release.
>
> The difference is already user visible: you can hotplug on ACPI, but can't on
> mptables.
>
> Yes, reading back the subject does sound confusing - a better one would probably
> be "provide interface for CPU hotplug on mptable platforms" or something similar.
>

So, are there any mptables platforms which support hotplug? If the
answer is "KVM" then the answer is that KVM needs to move to ACPI to get
the proper functionality; putting a hack in is really not okay.

-hpa


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