Re: Are pages allowed to cross PMA regions?


Andres Amaya Garcia
 

Thank you all for the valuable input!

In summary, it is possible to have virtual memory pages that straddle multiple PMA and PMP regions. There are simplifications or implementation decisions that can be made to deal with this situation: Limiting PMA/PMP regions to be >= 4KB, caching in TLB, attribute caches, etc.

However, the rules regarding some of these cases (misaligned accesses across regions, straddling, etc) appear to be rather loose in RISC V (see Allen Baum's message). Is there any ongoing work/plans to revisit the subject and perhaps clarify some of it in the Privileged Specification? If not, is it worth tracking this somewhere? Perhaps creating a GitHub issue? (P.S. I am new to the RISC V community, so don't know how to go about it if there is interest in the subject)

Once again, thanks for the help!

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