I've recently started getting into low level stuff and looking into bootloaders and operating systems etc...

As I understand it, for ARM processors at least, peripherals are initialized by the bootloader and then they are mapped into the physical memory space. From here, code can access the peripherals by simply writing values to the memory space mapped to the peripherals registers. Later if the chip has a MMU, it can be used to further remap into virtual memory spaces. Am I right?

What I don't understand are (assuming what I have said above is correct):

  • How does the bootloader initialize the peripherals if they haven't been mapped to an address space yet?
  • With virtual memory mapping, there are tables that tell the MMU where to map what. But what determines where peripherals are mapped in physical memory?
memory arm low-level
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