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Date: Mon, 12 Oct 2009 09:49:54 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: [Qemu-devel] Re: [PATCH v2 3/9] provide in-kernel ioapic
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To: Jamie Lokier <jamie@shareable.org>
Cc: Anthony Liguori <aliguori@us.ibm.com>, kvm-devel <kvm@vger.kernel.org>, Gleb Natapov <gleb@redhat.com>, Glauber Costa <glommer@redhat.com>, qemu-devel@nongnu.org, Juan Quintela <quintela@trasno.org>, Avi Kivity <avi@redhat.com>

Jamie Lokier wrote:
> Anthony Liguori wrote:
>   
>> We already have the single device model implementation and the 
>> limitations are well known.  The best way to move forward is for someone 
>> to send out patches implementing separate device models.
>>
>> At that point, it becomes a discussion of two concrete pieces of code 
>> verses hand waving.
>>     
>
> Out of curiosity now, what _are_ the behavioural differences between
> the in-kernel irqchip and the qemu one?
>
> Are the differences significant to guests, such that it might be
> necessary to disable the in-kernel irqchip for some guests, or
> conversely, necessary to use KVM for some guests?
>   

No, the behavior differences are not terribly significant for the apic.  
Disabling it is really most useful for debugging purposes.

Regards,

Anthony Liguori