| .. 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. |
