Hi Ayan, > On 9 Apr 2025, at 11:46, Ayan Kumar Halder <ayank...@amd.com> wrote: > > > On 09/04/2025 11:21, Luca Fancellu wrote: >> Hi Ayan, > Hi, >> >>> On 9 Apr 2025, at 11:07, Ayan Kumar Halder <ayank...@amd.com> wrote: >>> >>> >>> On 09/04/2025 09:26, Luca Fancellu wrote: >>>> Hi Ayan, >>> Hi Luca, >>>>>>> The point of the code was to don’t issue an isb() every time we change >>>>>>> the selector, >>>>>>> of course the code would be easier otherwise, but do we want to do that? >>>>>> Not sure if it is beneficial as you would need to use isb() from >>>>>> region16 onwards. >>>>> The isb() is issued only when changing the selector, so when you go from >>>>> reading/writing regions >>>>> from 0-15 to 16-31 for example, of course there is a case that if you >>>>> continuously write on region 15 >>>>> and 16 you would have to always change the selector, but it’s the less >>>>> impact we could have. >>>>> >>>>> armv8-R is even better since it’s able to address regions from 0 to 23 >>>>> without flushing the pipeline, >>>> ^— aarch32 :) >>> Can you point me to the document where you got this info ? >> was referring to the r52, of course you are more knowledgeable on the >> armv8-r aarch32 part, so ... > If you can point me to the page and section within R52 TRM, I can take a look > to see if I missed something (which isn't suprising as the docs are huge :))
Arm® Cortex®-R52 Processor TRM, r1p1, 8.5 MPU Register summary, I can see HPRBAR going from 0 to 24 (so I was wrong above, there should be 25 regions?). Anyway we should follow the armv8-r aarch32 specs here as you mentioned before, so max 32 region. Anyway you are the developer of the arm32 code so I’m ok with your choices! Cheers, Luca
