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Re: [Qemu-devel] [PATCH 1/6] target-arm: kvm: save/restore mp state
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 1/6] target-arm: kvm: save/restore mp state |
Date: |
Tue, 03 Mar 2015 18:10:12 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 03/03/2015 17:30, Alex Bennée wrote:
>> >
>>> >> Right now this is not migrated on ARM if I remember correctly, but
>>> >> perhaps you'll want to add it in the future.
>> >
>> > ...which is why we don't need to migrate this: it just means
>> > that migration during WFI causes an unnecessary-wakeup, which
>> > is architecturally fine.
> What happens when you boot a SMP system but only ever power up one of the
> CPUs? You can't just randomly start the second CPU if it's in the
> powered off state, who knows what it would do?
The second CPU would not be in the WFI state, which is what Peter is
talking about.
I agree that this state should be saved/restored. I'm just saying that
HALTED is not the right constant to use.
Paolo