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

[Jan Kiszka <jan.kiszka@siemens.com>]

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.
> Jan, can you be more specific on why it breaks? I'm double trying it
> here, and it works for me just fine.
> 

It locked up in the BIOS after reset from a booted SMP guest, somewhere
before selecting the boot device.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux