Documentation/arch/loongarch/booting.rst
.. SPDX-License-Identifier: GPL-2.0
:Author: Yanteng Si [email protected] :Date: 18 Nov 2022
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.
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 */