lidnariq wrote:
Part of the memory map is a direct fixed mapping from virtual addresses to physical addresses, with granularity of 512 MiB. (The entire virtual memory range from 0x8000_0000 through 0x9FFF_FFFF, as it says on the wiki, directly addresses physical memory from 0x0000_0000 through 0x1FFF_FFFF.
I understand, it means that this virtual memory, is never located in another place in ram but always in the addresses from 0x0000_0000 through 0x1FFF_FFFF, in ram
lidnariq wrote:
Physical addresses from 0x0000_0000 through 0x04FF_FFFF, and 0x1FC0_0000 through 0x1FCF_FFFF correspond to devices internal to the RCP; the rest is access to the Parallel Interface. Given how tricky direct PI interface is, I have a hunch that this direct map was only made available so that the PIF's initial program loader didn't have to use the DMA hardware.)
ok, so, knowing where the program can be located you do not need the DMA system with the MMU to do it, and it is also faster to access the RAM directly.
So the initial position of the program using the MMU is not fixed in RAM = another translation for the program segments, which is what happens when loading a rom through the MMU