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| -rw-r--r-- | Documentation/mips/booting.rst | 28 |
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diff --git a/Documentation/mips/booting.rst b/Documentation/mips/booting.rst new file mode 100644 index 000000000..7c18a4eab --- /dev/null +++ b/Documentation/mips/booting.rst @@ -0,0 +1,28 @@ +.. 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. |