A64/Memory map

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The full memory map can be found in the official A64 user manual, this table here just shows deviations from that (as found by experiments on the SoC) or annotations.

Memory Map

Start End Size Name Remarks
0x00000000 0x0000FFFF 64KiB BROM Only a small part is used (0x0000 ~ 0x8080)
0x00010000 0x00017FFF 32KiB SRAM A1 The Boot ROM loads the first user provided code (usually boot0 or U-Boot's SPL, loaded from eMMC, SD card, SPI flash or FEL) into this region and executes it.
0x00018000 0x00032FFF 108KiB SRAM C Contiguous with the SRAM A1.
Following the manual this region should be larger (160KiB, 0x18000-0x3FFFF). Also this region doesn't work reliably when AHB1 is clocked at 200MHz but well when clocked at 100MHz (which is the frequency used by FEL mode)[1].
0x00033000 0x0003FFFF 52KiB RAZ/WI The manual claims this is part of SRAM C, but this region is always read as zero with writes ignored.
0x00040000 0x00043FFF 16KiB arisc excp ARISC exception vectors: sparsely implemented, only one 32-bit word at each 256 Byte boundary, followed by a hardcoded OpenRISC NOP (0x15000000).
0x00044000 0x00053FFF 64KiB SRAM A2 This region is tightly coupled to the ARISC core, so OpenRISC code is normally loaded here.
0x01C28000 0x01C283FF 1KiB UART 0 This is the UART used by the firmware (boot0, ATF) and U-Boot.
0x40000000 0xFFFFFFFF 3GiB SDRAM DRAM space, up to 3GiB.


  1. http://irclog.whitequark.org/linux-sunxi/2016-06-29#16862925
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