.. SPDX-License-Identifier: GPL-2.0

BMIPS DeviceTree Booting
------------------------

  Some bootloaders only support a single entry point, at the start of the
  kernel image.  Other bootloaders will jump to the ELF start address.
  Both schemes are supported; CONFIG_BOOT_RAW=y and CONFIG_NO_EXCEPT_FILL=y,
  so the first instruction immediately jumps to kernel_entry().

  Similar to the arch/arm case (b), a DT-aware bootloader is expected to
  set up the following registers:

         a0 : 0

         a1 : 0xffffffff

         a2 : Physical pointer to the device tree block (defined in chapter
         II) in RAM.  The device tree can be located anywhere in the first
         512MB of the physical address space (0x00000000 - 0x1fffffff),
         aligned on a 64 bit boundary.

  Legacy bootloaders do not use this convention, and they do not pass in a
  DT block.  In this case, Linux will look for a builtin DTB, selected via
  CONFIG_DT_*.

  This convention is defined for 32-bit systems only, as there are not
  currently any 64-bit BMIPS implementations.