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TDA4VM: [TDA4VM]"mem_test" can access 2GB address range beyond physical 1.5GB on rank0

Joe Shen
Expert 3685 points
Part Number: TDA4VM

Dear Expert,

I ask the question on behalf of customer.

Customer is using 3GB Micron LPDDR4 on TDA4VM. We select “no_boot” mode and initial DDR with CCS gel files. After loading the “mem_test” app in PDK tomcu_r5f_0_0. The test can be passed from 0x8000_0000 to 0xFFFF_FFFF 2GB size.

Our questions is the DDR size in rank0 is only 1.5GB but why the “mem test” can read/write beyond 1.5G (0xE000_0000 to 0xFFFF_FFFF)?

Could you please help to check?

Regards

Joe

  • 0
    TI__Mastermind 38300 points

    Hi,

    My understanding is that:

    • You are using the EVM software configuration for 4GB total memory (2GB per rank)
    • Physical memory on custom board is only 1.5GB per rank
    • Question is why does memory space 1.5GB to 2GB work, if doesn't exist physically on rank 0?

    The ranks should be interleaved in the default software configuration, such that the lower 2GB of system memory maps to the lower 1GB of rank 0 / rank 1 of the DRAM.