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- .. 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.
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