Re: [PATCH 1/4] always halt non-bsp cpu.

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Glauber Costa wrote:
> On Wed, Jun 03, 2009 at 12:32:04AM +0200, Jan Kiszka wrote:
>> Glauber Costa wrote:
>>> On Wed, Jun 03, 2009 at 12:01:00AM +0200, Jan Kiszka wrote:
>>>> Glauber Costa wrote:
>>>>> On Tue, Jun 02, 2009 at 10:35:47PM +0200, Jan Kiszka wrote:
>>>>>> Glauber Costa wrote:
>>>>>>> This is not kvm specific, and should do fine in plain qemu
>>>>>> This is fine with plain qemu already. The problem, IIUC, is that
>>>>>> in-kernel kvm irqchip does not have a chance to remove the halted state
>>>>>> again. Did you test the effect of this patch on that scenario? What
>>>>>> makes it safe to be removed now?
>>>>> IIRC, the in kernel irqchip sets halted = 0 in the very beginning of
>>>>> the vcpu initialization.
>>>>>
>>>>> It is tested here with in-kernel irqchip and works, so probably not
>>>>> a problem, unless you can spot something.
>>>> At least your patch applied alone breaks -smp >1 here.
>>>>
>>>> But the whole management of env->halted for the in-kernel irqchip in
>>>> qemu-kvm is a bit hacky IMHO. Maybe it's time to rethink this. Would be
>>>> nice to always see a consistent halted in user space, specifically for
>>>> debugging purposes.
>>> out of curiosity: did you apply the whole series?
>> Meanwhile I did, but it makes no difference.
>>
> 
> Can you try putting the following patch before this one?

If it helps you to understand the issue, I will do so later.

But I *really* suggest to take this chance and develop in-kernel irqchip
support that does not mess with halted, rather keeps it consistent (on
register sync) and maybe adds exceptions from "if (!env->halted)" tests
where required. IMHO, this is mandatory for an upstream merge!

Jan

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