Re: [PATCH] ARMPkg: Unified the GIC base address variables as 64-bit width

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 24 October 2016 at 12:47, Ryan Harkin <ryan.harkin@linaro.org> wrote:
> On 24 October 2016 at 04:04, Dennis Chen <dennis.chen@arm.com> wrote:
>> Since ACPI spec defines the GIC base addresses (CPU interface,
>> Distributor and Redistributor*GICv3 only*) as 64-bit, so we should
>> define these corresponding base address variables as 64-bit instead of
>> 32-bit. This patch redefines them according to the ACPI spec.
>>
>
> Following on with Ard's comment on the earlier version, what happens
> if you want to use GICv3 on a 32bit system, eg the Cortex-A32 FVP
> models, which I believe [1] has GICv3?
>

I don't think that matters. GICv3 does not use MMIO for the CPU
interface anyway, and referring to the MMIO bits using 64-bit types is
unlikely to affect performance imo. From a functionality pov, those
top bits will simply be always zero (much like they are now on every
known ARM platform)

> [1] Go here and search for "gicv3"
> http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0834i/Chunk1955773768.html
>