ePMP update

Joe Xie

Hi TEE group,
I would like to give a quick update on ePMP spec.
Public review
We are still waiting for unpriv group to approve new CSR address assignment. It’s been pending for a while because there’re a few more specs to review and approve. We are trying to find ways to accelerate the approval process.
Spec update to support shared RO region
As some of you may aware, the TG had been discussing how to support shared RO region between M and sub-M mode.
After two meetings we tentatively concluded to propose repurposing LWRX = 1111 for shared RO region. The spec is updated with the new proposal, thanks to @Nick Kossifidis. And I copied the words here
The encoding pmpcfg.LRWX=1111 can be used for sharing data between M-mode and S/U mode, where both modes only have read-only access to the region. The region remains locked so that any further modifications to the configuration or address registers are ignored until a hard reset, unless mseccfg.RLB is set.
Please kindly review the change and provide feedback, I am also adding Andrew and tech-priv group for the review too. As usual we would need to start a new poll for the additional change, the poll will be started today and last for two weeks. After that, if it is approved, we would move on to update Spike, test-suit, SAIL model..etc.

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