Re: [Qemu-devel] [PATCH v12 5/5] hw/arm/virt: Add gic-version option to virt machine

[Peter Maydell]

On 4 September 2015 at 15:18, Pavel Fedin <address@hidden> wrote:
>  Hello!
>
>> I think we need to leave enough space for all of GICC/GICV/GICH
>> (that's 2 pages for GICC, 2 for GICV, 1 for GICH). They're optional
>> in a GICv3, but we may want them for emulation later on and if we
>> haven't left ourselves enough space we'll be a bit stuck.
>
>  Do we really need this? Are we going to have a model with HYP mode,
> inside of which we could run another model? BTW, our GICv2
> implementation also doesn't assume that it can have GICV/GICH.

Yes, I think that implementation of Hyp mode is very likely in
the future -- Xilinx want it, for instance.

>  Additionally, according to GIC-500 arch manual, GICC_DIR with
> affinity routing enabled has an offset of 0x10000, and it's 17
> pages instead of 2.

A register at offset 0x10000 means 2 64K pages, doesn't it?
Can you give a more exact reference to the bit of the manual
you mean?

>  Do we want to waste our precious address space?
>  But, well, i have calculated that we would have 124 maximum CPUs
> instead of 126. So - your final word on this?

Two fewer CPUs is not a big deal: anybody who finds 124
CPUs a restrictive limit would probably also find 126
CPUs too few. We can just add support for split redistributor
ranges in KVM before we get to the point where it's a problem.

thanks
-- PMM