doc: Add note about memory ranges

This commit is contained in:
Wladimir J. van der Laan 2019-05-12 20:12:38 +02:00
parent d9453e8a52
commit 819ad1665f

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@ -57,10 +57,21 @@ This is a rough memory map for the Kendryte K210 (as used on the Sipeed Maix boa
0x80600000 0x807fffff AI SRAM (cached)
0x88000000 0x8801ffff ROM
Source (paths refer to Kendryte SDK):
Source (paths refer to Kendryte stand-alone SDK):
- `lib/bsp/include/platform.h`
- `lib/drivers/apu.c`
- ROM dump
- ROM dump (there's a compiled device tree in there)
RAM ranges
-----------
- The 2MB of AI SRAM at `0x80600000` can be used as normal RAM when the KPU is not used.
- The `0x4xxxxxxx` range has a non-cached mirror of the SRAMs. Interestingly, floating point load instructions [don't work](https://github.com/rust-embedded/riscv-rt/issues/25#issuecomment-491524341) from this area.
- There is a mirror of the cached SRAM area at `0xffffffff80000000`, this is useful for the [medlow memory model](https://www.sifive.com/blog/all-aboard-part-4-risc-v-code-models).
- More generally, it looks like the upper 32 bits of the address are ignored.
Boot sequence
-------------