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Date: Fri, 22 Nov 2013 09:03:00 +0800
From: Li Guang <lig.fnst@cn.fujitsu.com>
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Subject: Re: [Qemu-devel] [PATCH 16/27] acpi: ich9: allow guest to clear SCI
 rised by GPE
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To: Igor Mammedov <imammedo@redhat.com>
Cc: peter.maydell@linaro.org, aliguori@amazon.com, stefanb@linux.vnet.ibm.com, qemu-devel@nongnu.org, Hu Tao <hutao@cn.fujitsu.com>, "Michael S. Tsirkin" <mst@redhat.com>, mjt@tls.msk.ru, mdroth@linux.vnet.ibm.com, armbru@redhat.com, vasilis.liaskovitis@profitbricks.com, quintela@redhat.com, kraxel@redhat.com, stefanha@redhat.com, pbonzini@redhat.com, marcel.a@redhat.com, lcapitulino@redhat.com, chegu_vinod@hp.com, afaerber@suse.de

Igor Mammedov wrote:
> On Thu, 21 Nov 2013 16:32:27 +0800
> Li Guang<lig.fnst@cn.fujitsu.com>  wrote:
>
>    
>> Michael S. Tsirkin wrote:
>>      
>>> On Thu, Nov 21, 2013 at 04:18:45PM +0800, Li Guang wrote:
>>>
>>>        
>>>> Hu Tao wrote:
>>>>
>>>>          
>>>>> On Thu, Nov 21, 2013 at 09:14:18AM +0200, Michael S. Tsirkin wrote:
>>>>>
>>>>>            
>>>>>> On Thu, Nov 21, 2013 at 03:38:37AM +0100, Igor Mammedov wrote:
>>>>>>
>>>>>>              
>>>>>>> it fixes IRQ storm since guest isn't able to lower SCI IRQ
>>>>>>> after it has been handled when it clears GPE event.
>>>>>>>
>>>>>>> Signed-off-by: Igor Mammedov<imammedo@redhat.com>
>>>>>>>
>>>>>>>                
>>>>>> The storm is only on memory hotplug right?
>>>>>>
>>>>>>              
>>>>> IIRC, it happens on cpu hotplug, too.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>            
>>>> :-), that made remember EC implementation,
>>>> with EC, SCI will be safer, I think.
>>>>
>>>>          
>>> Hmm you are saying let's use EC for memory hotplug?
>>>
>>>
>>>
>>>        
>> It can be a bridge between guest and QEMU,
>> with it, we may don't have to bother ASL writing
>> and south-bridge hardware related work(or very
>> little) if we implement EC correctly.
>>
>>      
> Wouldn't it require guest driver though?
> Beauty of ASL/GPE it's that it supported by Windows and Linux
> out of box.
>
>    

it did require guest driver, but as a ACPI standard device,
the driver is natively implemented by ACPI compatible OS.