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x86bootloaderosdevandroid-x86x86-emulation

Does ARM start in 16 bit real mode


A little bg - I just started OS Dev and am developing my own OS in assembly.

So as I have learned, x86 processors and others that emulate them(AMD?) start in 16 bit real mode for boot process and then can switch to protected mode to further bootstrap the OS or secondary bootloader and what not. (leave the modern BIOSes and UEFI's switching them to 32/64 bit part and then switching them back to 16 bit real mode part as that is irrelevant)

My simple question is - Do embedded devices that have ARM processors also do this? I mean do our smartphones switch to 16 bit real mode for the boot process?


Solution

  • No. "Real mode" is unique to the x86 architecture; it doesn't exist on ARM systems. They boot directly into a 32-bit mode.