LX2160A-RDB-B DRAM Address

kouno — Thu, 10 Feb 2022 03:12:30 GMT

Please tell me about LX2160A-RDB-B.
The LX2160A-RDB-B has 32GByte of DRAM.
There are two 16GByte DIMMs on the board.
The memory map, on the other hand, looks like this.

GPP DRAM Region #1 0x0000_8000_0000-0x0000_FFFF_FFFF (2GB)
GPP DRAM Region #2 0x0020_8000_0000-0x003F_FFFF_FFFF (126GB)
GPP DRAM Region #3 0x0060_0000_0000-0x007F_FFFF_FFFF (128GB)

What will be the physical address of the memory space that can actually be used?
Will the addresses for the two DIMMs be assigned to Region #2?
Or will the two DIMMs be assigned to Region #2 and Region #3 respectively?

0x0000_8000_0000-0x0000_FFFF_FFFF(2GB) + 0x0020_8000_0000-0x0023_FFFF_FFFF(14GB) + 0x0060_0000_0000-0x0063_FFFF_FFFF(16GB)
or
0x0000_8000_0000-0x0000_FFFF_FFFF(2GB) + 0x0020_8000_0000-0x0027_FFFF_FFFF(30GB)

Thanks

Re: LX2160A-RDB-B DRAM Address

ufedor — Thu, 10 Feb 2022 06:29:26 GMT

The ARM memory map places DRAM regions such that there are upper DRAM regions for 40-bit physical address space.

To achieve larger than 2 GB of DDR memory on a single chip select and to create a contiguous memory space to interleave DDR memory, a remapping logic is implemented. The remapping logic resides between the SoC space and DDR. The remapping logic, re-maps the SoC address to DDR physical address. The remapping logic is not visible or configurable by software.

The LX2160A remapping is shown below:

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LX2160A-RDB-B DRAM Address

Re: LX2160A-RDB-B DRAM Address