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29 lines
1 KiB
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29 lines
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.. SPDX-License-Identifier: GPL-2.0
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BMIPS DeviceTree Booting
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------------------------
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Some bootloaders only support a single entry point, at the start of the
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kernel image. Other bootloaders will jump to the ELF start address.
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Both schemes are supported; CONFIG_BOOT_RAW=y and CONFIG_NO_EXCEPT_FILL=y,
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so the first instruction immediately jumps to kernel_entry().
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Similar to the arch/arm case (b), a DT-aware bootloader is expected to
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set up the following registers:
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a0 : 0
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a1 : 0xffffffff
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a2 : Physical pointer to the device tree block (defined in chapter
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II) in RAM. The device tree can be located anywhere in the first
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512MB of the physical address space (0x00000000 - 0x1fffffff),
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aligned on a 64 bit boundary.
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Legacy bootloaders do not use this convention, and they do not pass in a
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DT block. In this case, Linux will look for a builtin DTB, selected via
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CONFIG_DT_*.
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This convention is defined for 32-bit systems only, as there are not
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currently any 64-bit BMIPS implementations.
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