Describes the meaning and value of the image header field.
Suggested-by: Xiaotian Wu <wuxiaotian@xxxxxxxxxxx>
Signed-off-by: Yanteng Si <siyanteng@xxxxxxxxxxx>
---
Documentation/loongarch/booting.rst | 43 +++++++++++++++++++++++++++++
Documentation/loongarch/index.rst | 1 +
2 files changed, 44 insertions(+)
create mode 100644 Documentation/loongarch/booting.rst
diff --git a/Documentation/loongarch/booting.rst b/Documentation/loongarch/booting.rst
new file mode 100644
index 000000000000..d893f495ca58
--- /dev/null
+++ b/Documentation/loongarch/booting.rst
@@ -0,0 +1,43 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================
+Booting Linux/LoongArch
+=======================
+
+:Author: Yanteng Si <siyanteng@xxxxxxxxxxx>
+:Date: 18 Nov 2022
+
+Bootloader passing parameters to the 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 FDT, 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 isfully 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 0 /* 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 */
+
diff --git a/Documentation/loongarch/index.rst b/Documentation/loongarch/index.rst
index aaba648db907..df0174d6d227 100644
--- a/Documentation/loongarch/index.rst
+++ b/Documentation/loongarch/index.rst
@@ -10,6 +10,7 @@ LoongArch Architecture
introduction
irq-chip-model
+ booting
features
--
2.31.1
