Re: [PATCH v6 00/11] xen/arm: Add Armv8-R64 MPU support to Xen - Part#1

[Julien Grall <julien@xxxxxxx>]

Hi Wei,

On 04/11/2022 10:07, Wei Chen wrote:
> The Armv-R architecture profile was designed to support use cases
> that have a high sensitivity to deterministic execution. (e.g.
> Fuel Injection, Brake control, Drive trains, Motor control etc)
>
> Arm announced Armv8-R in 2013, it is the latest generation Arm
> architecture targeted at the Real-time profile. It introduces
> virtualization at the highest security level while retaining the
> Protected Memory System Architecture (PMSA) based on a Memory
> Protection Unit (MPU). In 2020, Arm announced Cortex-R82,
> which is the first Arm 64-bit Cortex-R processor based on Armv8-R64.
> The latest Armv8-R64 document can be found [1]. And the features of
> Armv8-R64 architecture:
>    - An exception model that is compatible with the Armv8-A model
>    - Virtualization with support for guest operating systems
>    - PMSA virtualization using MPUs In EL2.
>    - Adds support for the 64-bit A64 instruction set.
>    - Supports up to 48-bit physical addressing.
>    - Supports three Exception Levels (ELs)
>          - Secure EL2 - The Highest Privilege
>          - Secure EL1 - RichOS (MMU) or RTOS (MPU)
>          - Secure EL0 - Application Workloads
>   - Supports only a single Security state - Secure.
>   - MPU in EL1 & EL2 is configurable, MMU in EL1 is configurable.
>
> These patch series are implementing the Armv8-R64 MPU support
> for Xen, which are based on the discussion of
> "Proposal for Porting Xen to Armv8-R64 - DraftC" [1].
>
> We will implement the Armv8-R64 and MPU support in three stages:
> 1. Boot Xen itself to idle thread, do not create any guests on it.
I read this as I can build Xen and see it boots (not creating domain). 
However... HAS_MPU is not defined and I was expecting mm.c to be 
modified to cater the MPU support. So I am a bit ensure what the series 
is actually doing.
Cheers,

--
Julien Grall