Commit 38eb496d authored by Yanteng Si's avatar Yanteng Si Committed by Huacai Chen
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docs/LoongArch: Add booting description 



1, Describe the information passed from BootLoader to kernel.
2, Describe the meaning and values of the kernel image header field.

Suggested-by: default avatarXiaotian Wu <wuxiaotian@loongson.cn>
Signed-off-by: default avatarYanteng Si <siyanteng@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent b681604e

Documentation/loongarch/booting.rst

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.. SPDX-License-Identifier: GPL-2.0



=======================

Booting Linux/LoongArch

=======================



:Author: Yanteng Si <siyanteng@loongson.cn>

:Date:   18 Nov 2022



Information passed from BootLoader to kernel

============================================



LoongArch supports ACPI and FDT. The information that needs to be passed

to the kernel includes the memmap, the initrd, the command line, optionally

the ACPI/FDT tables, and so on.



The kernel is passed the following arguments on `kernel_entry` :



      - a0 = efi_boot: `efi_boot` is a flag indicating whether

        this boot environment is fully UEFI-compliant.



      - a1 = cmdline: `cmdline` is a pointer to the kernel command line.



      - a2 = systemtable: `systemtable` points to the EFI system table.

        All pointers involved at this stage are in physical addresses.



Header of Linux/LoongArch kernel images

=======================================



Linux/LoongArch kernel images are EFI images. Being PE files, they have

a 64-byte header structured like::



	u32	MZ_MAGIC                /* "MZ", MS-DOS header */

	u32	res0 = 0                /* Reserved */

	u64	kernel_entry            /* Kernel entry point */

	u64	_end - _text            /* Kernel image effective size */

	u64	load_offset             /* Kernel image load offset from start of RAM */

	u64	res1 = 0                /* Reserved */

	u64	res2 = 0                /* Reserved */

	u64	res3 = 0                /* Reserved */

	u32	LINUX_PE_MAGIC          /* Magic number */

	u32	pe_header - _head       /* Offset to the PE header */

Documentation/loongarch/index.rst

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@@ -9,6 +9,7 @@ LoongArch Architecture 
   :numbered:



   introduction

   booting

   irq-chip-model



   features