8. 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) |