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Re: [PATCH 5/5] xen/arm: map static memory on demand
- To: Hari Limaye <Hari.Limaye@xxxxxxx>
- From: "Orzel, Michal" <michal.orzel@xxxxxxx>
- Date: Wed, 27 Aug 2025 18:07:06 +0200
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- Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "Luca Fancellu" <Luca.Fancellu@xxxxxxx>, Penny Zheng <Penny.Zheng@xxxxxxx>, "Stefano Stabellini" <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, "Bertrand Marquis" <Bertrand.Marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Wei Chen <Wei.Chen@xxxxxxx>
- Delivery-date: Wed, 27 Aug 2025 16:07:23 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 27/08/2025 14:31, Hari Limaye wrote:
> Hi Michal,
>
>> On 22 Aug 2025, at 08:50, Orzel, Michal <michal.orzel@xxxxxxx> wrote:
>>
>>
>>
>> On 30/07/2025 10:45, Hari Limaye wrote:
>>> From: Penny Zheng <Penny.Zheng@xxxxxxx>
>>>
>>> In the function `init_staticmem_pages` we need to have mapped static
>>> memory banks for initialization. Unlike on an MMU system, we cannot map
>>> the entire RAM on an MPU system as we have a limited number of MPU
>>> memory regions. To solve this, transiently map the static memory banks
>>> for initialization.
>> How does this correspond to Arm32 MPU (R52), where all of the RAM will be
>> covered? I don't think 'transient' mappings will be needed there but all of
>> your
>> work targets common (i.e. not only Arm64) MPU code.
>>
>> ~Michal
>>
>
> Hm fair point - when this series was submitted to the ML, I had no knowledge
> of the intention for all of the RAM to be mapped on Arm32 MPU systems and
> imagined that things would be more aligned here.
>
> Are happy for this to remain common for now? Or would you prefer it to be
> split off?
Let it be common for now. We can revisit it after the release to align on the
final approach.
~Michal
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