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MMU: force identity mapping without pages?

hi,

on a cortex a53, I would like to get the best of both worlds. Having dcache enabled but no page walk in case of a miss.

I want no memory protection because we manage the whole system ( kind of baremetal processes)

Is there a way to tell the mmu controller that we are in identity mapping for the whole memory available, so that a page walk is not triggered?

thanks

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  • That could be due to the nature of the applications that the R-profile targets.

    For e.g., r8 has been targeted at "Highest performance 5G modem and storage". I think that one could find that processor on hard disks, storage arrays, cellphones, or routers, but a board might be hard to come by.

    There's "R-Car H3" SoC which contains r7.

    Boards containing r4 and r5 are listed by Arm here, while those containing r5 and r7, here.

    There are also software models which can be programmed.

    Edit: It is likely that even the devices, which a particular CPU targets, might not be implemented yet.

  • I am actually willing to design my own board.

    Now, I should ask a chinese pcba and check if I am lucky :)

  • Nice. :)

    And for the CPU chip, Arm might know if there are any licensees. Wikipedia has a list of them.

    Edit: If there are no vendors, does a FPGA solution fare well? I would not know if it is even possible with Arm, but I know Google and certain other companies run (or used to run) their AI processing on custom FPGA solutions.

  • a fpga would be really cool. My problem with fpga is the price. I need a prototype and then a first batch of 2000 boards. So I guess I am better with something less expensive for a retail price of around 35€..

  • I was dead wrong. Lattice fpgas are dirt cheap.

    There is my take!!! Thank you so much for putting me on the right track. You rock.