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TMS570LC4357: NMPU access-privilege configuration for dma

Max Wittekind
Expert 1875 points
Part Number: TMS570LC4357

Hi experts,

DMA and ETH are non-privileged bus-masters according to the Safety Manual, however when setting the access permissions through the NMPU there is an option to configure addresses as based on priviliged and user mode.

What confuses me is, that a configuration of an adress space as read/write privileged would be the same as no access for DMA, since it can only access memory in user mode.

My Question ist: Why is there an option tp configure mempry based on privileged and user mode, when there is no way to configure the dma privileged?
How should this be used?

Thank you and best regards,
Max

  • 0
    TI__Guru 69701 points

    Hi Max,

    Started working on your issue and will provide an update soon.

    --

    Thanks & regards,
    Jagadish.

  • 0 in reply to jagadish gundavarapu
    TI__Guru 69701 points

    Hi Max,

    Max Wittekind said:
    My Question ist: Why is there an option tp configure mempry based on privileged and user mode, when there is no way to configure the dma privileged?
    How should this be used?

    As per my understanding, the configuration of memory to the privileged mode is not intended for DMA access. This configuration helps to control the CPU access to the memory, as we know the CPU can operate in different modes (User and Privilege), so that we can restrict processor to access certain area if it is operating in user mode by configuring memory to privilege mode. In this way we can control the CPU access to the memory as per user requirements.

    In conclusion, If DMA need to access certain memory then it should be configured in user mode. And memory access permissions are not meant for DMA and they are for CPU.

    --
    Thanks & regards,
    Jagadish.