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From: Peter Maydell <peter.maydell@linaro.org>
Date: Wed, 21 Oct 2015 15:46:22 +0100
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Subject: Re: [Qemu-devel] [PATCH RFC V5 6/9] hw/intc: arm_gicv3_spi_its
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To: Pavel Fedin <p.fedin@samsung.com>
Cc: Eric Auger <eric.auger@linaro.org>, Shlomo Pongratz <shlomo.pongratz@huawei.com>, Shlomo Pongratz <shlomopongratz@gmail.com>, QEMU Developers <qemu-devel@nongnu.org>, Shannon Zhao <shannon.zhao@linaro.org>, Ashok Kumar <ashoks@broadcom.com>, Igor Mammedov <imammedo@redhat.com>

On 21 October 2015 at 15:41, Pavel Fedin <p.fedin@samsung.com> wrote:
>  Hello!
>
>> I just wanted to understand. I don't have any preferences.
>
>  In other words, in short: spec says that ITS is optional, so
> we can implement it as a separate component, which gets attached
> to the GIC using some specified interface. It's not a problem
> to design such an interface. Actually, i believe real HW does
> the same thing.

For hw it's a design choice: hardware can either have the ITS as
an extra component on the side that only talks to the
redistributors via (impdef) redistributor registers; or
it can be an integrated part of the GIC that's just directly
connected internally.

For QEMU we could in theory do either; I was leaning towards
direct connection just because on the KVM side the in-kernel
GIC isn't going to separate them out as two distinct things.
But even there we can as you say sensibly model the ITS
as its own QOM object with a fairly well-defined interface
to the rest of the GIC.

thanks
-- PMM