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

[Peter Maydell]

On 4 September 2015 at 08:26, Pavel Fedin <address@hidden> wrote:
>  Hello!
>
>> Why have separate ITS_CONTROL and ITS_TRANSLATION entries, given
>> that the ITS pages are architecturally required to be contiguous
>> and the dt binding doesn't require you to specify the two addresses
>> separately?
>
>  It is more convenient for ITS implementation. I already have
> the code for it, and for ITS device it is useful to have two
> separate sysbus-mmio regions, one for control and one for
> translation. Because control area is fed to KVM and translation
> area is handled by qemu in userspace, because it has to catch
> writes and inject them as KVM_SIGNAL_MSI ioctl's. So, i have to
> map two regions, therefore i need two bases. Sizes are just added
> together when i create DT binding.

This is an internal detail of the device's implementation, so
you shouldn't expose it to users of the device. Create a single
128K container memory region, and map your two 64K regions
into it. Then just expose the one container region from the
GIC device.

thanks
-- PMM