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OMAPL138 memory protection questions

pradhyum
Expert 3385 points
Other Parts Discussed in Thread: OMAPL138

Hello:

I got the following questions from a customer. Can I get some guidance?

  1. Can the ARM9 running in privileged mode under any circumstances read the L2 and L1 memories of the DSP once the protection is enabled via L2MPPA registers and L2MPLKCMD registers?
  2. Does ARM9 have access to any DSP protection registers at 0x01840000-0x184FFFF at any time?
  3. Can ARM9 gain access to the contents of L2 memories by placing DSP in reset states?

Thanks,

Pradhyum

  • 0
    TI__Guru* 83885 points

    pradhyum said:
    Can the ARM9 running in privileged mode under any circumstances read the L2 and L1 memories of the DSP once the protection is enabled via L2MPPA registers and L2MPLKCMD registers?

    No, this should happen. Once the MPPA etc are setup properly the DSP memories should be accessible as specified via MPPA settings etc and will not allow illegal access (and should generate memory protection exceptions)

    pradhyum said:
    Does ARM9 have access to any DSP protection registers at 0x01840000-0x184FFFF at any time?

    No, none of the bus masters including ARM9 have access to any DSP internal registers at any time. By DSP internal registers I mean all the registers specified under section 3.5.2.4 in the OMAPL138 datasheet. Only DSP can access these registers.

    pradhyum said:
    Can ARM9 gain access to the contents of L2 memories by placing DSP in reset states?

    If by DSP reset state you meant DSP held in Local Reset via PSC control, then yes, in this state ARM9 can access L2 memory. I am assuming this question is independent of the queries on the MPPA settings above. I am not sure on what the behavior would be if the MPPAs were previously configured to prevent ARM9 from accessing L2, and then DSP is held in local reset, if this is relevant w.r.t to the question above, then I can chekc with the arch team on this.

    Regards

    Mukul