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Date: Tue, 14 Aug 2012 13:05:11 +0200
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Qemu-devel] [PATCH] kvm-all.c: Move init of
	irqchip_inject_ioctl out of kvm_irqchip_create()
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To: Avi Kivity <avi@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Marcelo Tosatti <mtosatti@redhat.com>, qemu-devel@nongnu.org, kvm@vger.kernel.org, patches@linaro.org

On 2012-08-14 13:01, Avi Kivity wrote:
> On 08/14/2012 10:33 AM, Jan Kiszka wrote:
>>
>> KVM_IRQ_LINE is old-style, deprecated, KVM_IRQ_LINE_STATUS (i.e
>> injection with feedback to allow lost-tick compensation) is the current
>> standard that other archs should pick up.
> 
> KVM_IRQ_LINE_STATUS may not make sense on all architectures.
> 
> I don't think we're really deprecating KVM_IRQ_LINE or discouraging its
> use.  It's not like the kernel-allocated memory slot ioctls.

I do not think it makes sense to provide both interfaces long term
(provided we ever do a cut). Also, it's almost trivial to provide the
add-on feature of KVM_IRQ_LINE_STATUS, and it keeps the door open for
IRQ decoalescing. If there is no way for an arch to detect coalescing,
it can still return >0 unconditionally.

Jan

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