Re: [platforms: PATCH 08/13] Marvell/Armada: Modify GICC alias

[Leif Lindholm <leif.lindholm@linaro.org>]

On Mon, Oct 09, 2017 at 07:00:57PM +0200, Marcin Wojtas wrote:
> From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> 
> The GIC architecture mandates that the CPU interface, which consists
> of 2 consecutive 4 KB frames, can be mapped using separate mappings.
> Since this is problematic on 64 KB pages, the MMU-400 aliases each
> frame 16 times, and the two consecutive frames can be found at offset
> 0xf000. This patch is intended to expose correct GICC alias via
> MADT, once ACPI support is added.

I'm afraid I don't quite understand this message.

The change seems to be that the InterfaceBase moves from the first 4KB
alias inside a 64KB page to the last alias within the same page.
That seems valid, but I don't see how it resolves anything described
in this message?

/
    Leif

> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Signed-off-by: Marcin Wojtas <mw@semihalf.com>
> ---
>  Platform/Marvell/Armada/Armada.dsc.inc | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/Platform/Marvell/Armada/Armada.dsc.inc b/Platform/Marvell/Armada/Armada.dsc.inc
> index 5071bd5..bd2336f 100644
> --- a/Platform/Marvell/Armada/Armada.dsc.inc
> +++ b/Platform/Marvell/Armada/Armada.dsc.inc
> @@ -263,7 +263,14 @@
>  
>    # ARM Generic Interrupt Controller
>    gArmTokenSpaceGuid.PcdGicDistributorBase|0xF0210000
> -  gArmTokenSpaceGuid.PcdGicInterruptInterfaceBase|0xF0220000
> +
> +  #
> +  # NOTE: the GIC architecture mandates that the CPU interface, which consists
> +  # of 2 consecutive 4 KB frames, can be mapped using separate mappings.
> +  # Since this is problematic on 64 KB pages, the MMU-400 aliases each frame
> +  # 16 times, and the two consecutive frames can be found at offset 0xf000
> +  #
> +  gArmTokenSpaceGuid.PcdGicInterruptInterfaceBase|0xF022F000
>  
>    # ARM Architectural Timer Support
>    gArmTokenSpaceGuid.PcdArmArchTimerFreqInHz|25000000
> -- 
> 1.8.3.1
>