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diff --git a/Documentation/loongarch/booting.rst b/Documentation/loongarch/booting.rst new file mode 100644 index 000000000..91eccd410 --- /dev/null +++ b/Documentation/loongarch/booting.rst @@ -0,0 +1,42 @@ +.. 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 */ |