10. Zero Page¶
The additional fields in struct boot_params as a part of 32-bit boot protocol of kernel. These should be filled by bootloader or 16-bit real-mode setup code of the kernel. References/settings to it mainly are in:
arch/x86/include/uapi/asm/bootparam.h
Offset/Size |
Proto |
Name |
Meaning |
000/040 |
ALL |
screen_info |
Text mode or frame buffer information (struct screen_info) |
040/014 |
ALL |
apm_bios_info |
APM BIOS information (struct apm_bios_info) |
058/008 |
ALL |
tboot_addr |
Physical address of tboot shared page |
060/010 |
ALL |
ist_info |
Intel SpeedStep (IST) BIOS support information (struct ist_info) |
080/010 |
ALL |
hd0_info |
hd0 disk parameter, OBSOLETE!! |
090/010 |
ALL |
hd1_info |
hd1 disk parameter, OBSOLETE!! |
0A0/010 |
ALL |
sys_desc_table |
System description table (struct sys_desc_table), OBSOLETE!! |
0B0/010 |
ALL |
olpc_ofw_header |
OLPC’s OpenFirmware CIF and friends |
0C0/004 |
ALL |
ext_ramdisk_image |
ramdisk_image high 32bits |
0C4/004 |
ALL |
ext_ramdisk_size |
ramdisk_size high 32bits |
0C8/004 |
ALL |
ext_cmd_line_ptr |
cmd_line_ptr high 32bits |
140/080 |
ALL |
edid_info |
Video mode setup (struct edid_info) |
1C0/020 |
ALL |
efi_info |
EFI 32 information (struct efi_info) |
1E0/004 |
ALL |
alt_mem_k |
Alternative mem check, in KB |
1E4/004 |
ALL |
scratch |
Scratch field for the kernel setup code |
1E8/001 |
ALL |
e820_entries |
Number of entries in e820_table (below) |
1E9/001 |
ALL |
eddbuf_entries |
Number of entries in eddbuf (below) |
1EA/001 |
ALL |
edd_mbr_sig_buf_entries |
Number of entries in edd_mbr_sig_buffer (below) |
1EB/001 |
ALL |
kbd_status |
Numlock is enabled |
1EC/001 |
ALL |
secure_boot |
Secure boot is enabled in the firmware |
1EF/001 |
ALL |
sentinel |
Used to detect broken bootloaders |
290/040 |
ALL |
edd_mbr_sig_buffer |
EDD MBR signatures |
2D0/A00 |
ALL |
e820_table |
E820 memory map table (array of struct e820_entry) |
D00/1EC |
ALL |
eddbuf |
EDD data (array of struct edd_info) |