1.. SPDX-License-Identifier: GPL-2.0
2
3=========
4Zero Page
5=========
6The additional fields in struct boot_params as a part of 32-bit boot
7protocol of kernel. These should be filled by bootloader or 16-bit
8real-mode setup code of the kernel. References/settings to it mainly
9are in::
10
11  arch/x86/include/uapi/asm/bootparam.h
12
13===========	=====	=======================	=================================================
14Offset/Size	Proto	Name			Meaning
15
16000/040		ALL	screen_info		Text mode or frame buffer information
17						(struct screen_info)
18040/014		ALL	apm_bios_info		APM BIOS information (struct apm_bios_info)
19058/008		ALL	tboot_addr      	Physical address of tboot shared page
20060/010		ALL	ist_info		Intel SpeedStep (IST) BIOS support information
21						(struct ist_info)
22070/008		ALL	acpi_rsdp_addr		Physical address of ACPI RSDP table
23080/010		ALL	hd0_info		hd0 disk parameter, OBSOLETE!!
24090/010		ALL	hd1_info		hd1 disk parameter, OBSOLETE!!
250A0/010		ALL	sys_desc_table		System description table (struct sys_desc_table),
26						OBSOLETE!!
270B0/010		ALL	olpc_ofw_header		OLPC's OpenFirmware CIF and friends
280C0/004		ALL	ext_ramdisk_image	ramdisk_image high 32bits
290C4/004		ALL	ext_ramdisk_size	ramdisk_size high 32bits
300C8/004		ALL	ext_cmd_line_ptr	cmd_line_ptr high 32bits
3113C/004		ALL	cc_blob_address		Physical address of Confidential Computing blob
32140/080		ALL	edid_info		Video mode setup (struct edid_info)
331C0/020		ALL	efi_info		EFI 32 information (struct efi_info)
341E0/004		ALL	alt_mem_k		Alternative mem check, in KB
351E4/004		ALL	scratch			Scratch field for the kernel setup code
361E8/001		ALL	e820_entries		Number of entries in e820_table (below)
371E9/001		ALL	eddbuf_entries		Number of entries in eddbuf (below)
381EA/001		ALL	edd_mbr_sig_buf_entries	Number of entries in edd_mbr_sig_buffer
39						(below)
401EB/001		ALL     kbd_status      	Numlock is enabled
411EC/001		ALL     secure_boot		Secure boot is enabled in the firmware
421EF/001		ALL	sentinel		Used to detect broken bootloaders
43290/040		ALL	edd_mbr_sig_buffer	EDD MBR signatures
442D0/A00		ALL	e820_table		E820 memory map table
45						(array of struct e820_entry)
46D00/1EC		ALL	eddbuf			EDD data (array of struct edd_info)
47===========	=====	=======================	=================================================
48