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Bare metal, Assembly language • Re: System MMU existence/location on Pi 4B

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this is how it worked on the pi0-pi3, you have 64 pages of 16mb each, and that configures the mapping from "arm physical" to the VC4 bus
only the VPU can configure it, and 99% of the time, you dont need to mess with any of it
I was half asleep when I wrote my previous comment, so one thing that didn't cross my mind back then but I remembered later is that they might be able to indirectly access that MMU from the ARM cores using the DMA controller, which according to what I recall from the data-sheet, is a bus master and most of its channels can access the full 35-bit address space of the BCM2711. If this holds then the only small yet fundamental detail left to guess is the actual location of those registers.
yep, you can also use the vpu execute code mailbox

https://github.com/ali1234/vcpoke
this lets you do a simple 32bit r/w on demand, without having to reserve a dma channel

Statistics: Posted by cleverca22 — Sun Sep 07, 2025 4:27 am



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