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)
22080/010		ALL	hd0_info		hd0 disk parameter, OBSOLETE!!
23090/010		ALL	hd1_info		hd1 disk parameter, OBSOLETE!!
240A0/010		ALL	sys_desc_table		System description table (struct sys_desc_table),
25						OBSOLETE!!
260B0/010		ALL	olpc_ofw_header		OLPC's OpenFirmware CIF and friends
270C0/004		ALL	ext_ramdisk_image	ramdisk_image high 32bits
280C4/004		ALL	ext_ramdisk_size	ramdisk_size high 32bits
290C8/004		ALL	ext_cmd_line_ptr	cmd_line_ptr high 32bits
30140/080		ALL	edid_info		Video mode setup (struct edid_info)
311C0/020		ALL	efi_info		EFI 32 information (struct efi_info)
321E0/004		ALL	alt_mem_k		Alternative mem check, in KB
331E4/004		ALL	scratch			Scratch field for the kernel setup code
341E8/001		ALL	e820_entries		Number of entries in e820_table (below)
351E9/001		ALL	eddbuf_entries		Number of entries in eddbuf (below)
361EA/001		ALL	edd_mbr_sig_buf_entries	Number of entries in edd_mbr_sig_buffer
37						(below)
381EB/001		ALL     kbd_status      	Numlock is enabled
391EC/001		ALL     secure_boot		Secure boot is enabled in the firmware
401EF/001		ALL	sentinel		Used to detect broken bootloaders
41290/040		ALL	edd_mbr_sig_buffer	EDD MBR signatures
422D0/A00		ALL	e820_table		E820 memory map table
43						(array of struct e820_entry)
44D00/1EC		ALL	eddbuf			EDD data (array of struct edd_info)
45===========	=====	=======================	=================================================
46