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Date: Sun, 22 Aug 2010 16:06:04 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH v2 0/7] APIC/IOAPIC cleanup
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To: Avi Kivity <avi@redhat.com>
Cc: Blue Swirl <blauwirbel@gmail.com>, "Liu >> \"Liu,
	Jinsong\"" <jinsong.liu@intel.com>, qemu-devel <qemu-devel@nongnu.org>, Paul Brook <paul@codesourcery.com>

On 08/22/2010 03:33 PM, Avi Kivity wrote:
>  On 08/22/2010 11:03 PM, Anthony Liguori wrote:
>> On 08/22/2010 02:44 PM, Avi Kivity wrote:
>>>> No more MI diamond and all devices have DeviceStates.  
>>>> Coincidentally, it matches more closely how hardware works..
>>>>
>>>
>>>
>>> Well, I agree, but I honestly lost the context.  How does this 
>>> relate to the APIC and cpu hotplug?
>>
>> My original assertion was that the local APIC is not a DeviceState, 
>> but rather it's a CPU feature.
>>
>> If you look at some of the magic that apic.c has to do in the IO 
>> callbacks, it should be clear that it's special. 
>
> It's special in that it is connected to a cpu core.  So's the RTL8139 
> device, on one hand connected to a PCI bus, on the other hand 
> connected to a PHY (netdev in qemu).
>
>> In the not too distant future, I'd like to move apic.c to 
>> target-i386.  There should be no need to explicitly instantiate it 
>> when you instantiate a CPU.
>
> But then there's a need explicitly not to instantiate it when using 
> -isapc.

No.  isapc has nothing to do with whether a CPU has a local APIC.

You don't instantiate the local APIC if you create a 486 CPU.  If you 
create an isapc with a pentium processor, it's going to have a local 
APIC although it's irrelevant as it's fully compatible with the 486.

Regards,

Anthony Liguori