Re: [PATCH v3 2/6] xen/arm: mpu: Introduce choice between MMU and MPU

[Julien Grall <julien@xxxxxxx>]

Hi,

On 10/10/2024 15:03, Ayan Kumar Halder wrote:
> There are features in the forthcoming patches which are dependent on
> MPU. For eg fixed start address.
> Also, some of the Xen features (eg STATIC_MEMORY) will be selected
> by the MPU configuration.
>
> Thus, this patch introduces a choice between MMU and MPU for the type
> of memory management system. By default, MMU is selected.
> MPU is now gated by UNSUPPORTED.
>
> Update SUPPORT.md to state that the support for MPU is experimental.
>
> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
With one remark below:

Acked-by: Julien Grall <jgrall@xxxxxxxxxx>

> ---
> Changes from :-
>
> v1 - 1. Reworded the help messages.
> 2. Updated Support.md.
>
> v2 - 1. Reworded the help message.
>
>   SUPPORT.md                     |  1 +
>   xen/arch/arm/Kconfig           | 17 ++++++++++++++++-
>   xen/arch/arm/platforms/Kconfig |  2 +-
>   3 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/SUPPORT.md b/SUPPORT.md
> index 23dd7e6424..3f6d788a43 100644
> --- a/SUPPORT.md
> +++ b/SUPPORT.md
> @@ -40,6 +40,7 @@ supported in this document.
>   
>       Status, Xen in AArch64 mode: Supported
>       Status, Xen in AArch32 mode: Tech Preview
> +    Status, Xen with MPU: Experimental
Maybe mention Armv8-R?

>       Status, Cortex A57 r0p0-r1p1: Supported, not security supported
>       Status, Cortex A77 r0p0-r1p0: Supported, not security supported
>   
> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
> index 323c967361..ed92eb67cb 100644
> --- a/xen/arch/arm/Kconfig
> +++ b/xen/arch/arm/Kconfig
> @@ -58,10 +58,25 @@ config PADDR_BITS
>         default 40 if ARM_PA_BITS_40
>         default 48 if ARM_64
>   
> +choice
> +       prompt "Memory management system"
> +       default MMU
> +       help
> +         User can choose between the different forms of memory management 
> system.
> +
>   config MMU
> -       def_bool y
> +       bool "MMU"
>         select HAS_PMAP
>         select HAS_VMAP
> +       help
> +         Select it if you plan to run Xen on A-profile Armv7+
> +
> +config MPU
> +       bool "MPU" if UNSUPPORTED
> +       help
> +         Memory Protection Unit (MPU). Select if you plan to run Xen on ARMv8-R
> +         systems supporting EL2. (UNSUPPORTED)
> +endchoice
>   
>   source "arch/Kconfig"
>   
> diff --git a/xen/arch/arm/platforms/Kconfig b/xen/arch/arm/platforms/Kconfig
> index 76f7e76b1b..02322c259c 100644
> --- a/xen/arch/arm/platforms/Kconfig
> +++ b/xen/arch/arm/platforms/Kconfig
> @@ -1,5 +1,5 @@
>   choice
> -       prompt "Platform Support"
> +       prompt "Platform Support" if MMU
>         default ALL_PLAT
>         help
>         Choose which hardware platform to enable in Xen.
--
Julien Grall