Requirements For Multiboot
We need to understand required information for Multiboot Specification, common information and arch-specific information.
Information is divided into the information passed from a boot loader to an OS image and that passed from an OS image to a boot loader. In Multiboot Specification, the former is called "Multiboot Information", while the latter is "Multiboot Header".
Multiboot Header
- Multiboot is neutral to any executable format, so it must work with, for example, ELF, variants of a.out and PE.
Multiboot Information
- This information must be easy to interpret.
For reference, here is the old GRUB multiboot structure. Most of the fields do not make sense outside of x86:
struct grub_multiboot_info
{
/* MultiBoot info version number */
grub_uint32_t flags;
/* Available memory from BIOS */
grub_uint32_t mem_lower;
grub_uint32_t mem_upper;
/* "root" partition */
grub_uint32_t boot_device;
/* Kernel command line */
grub_uint32_t cmdline;
/* Boot-Module list */
grub_uint32_t mods_count;
grub_uint32_t mods_addr;
grub_uint32_t syms[4];
/* Memory Mapping buffer */
grub_uint32_t mmap_length;
grub_uint32_t mmap_addr;
/* Drive Info buffer */
grub_uint32_t drives_length;
grub_uint32_t drives_addr;
/* ROM configuration table */
grub_uint32_t config_table;
/* Boot Loader Name */
grub_uint32_t boot_loader_name;
/* APM table */
grub_uint32_t apm_table;
/* Video */
grub_uint32_t vbe_control_info;
grub_uint32_t vbe_mode_info;
grub_uint16_t vbe_mode;
grub_uint16_t vbe_interface_seg;
grub_uint16_t vbe_interface_off;
grub_uint16_t vbe_interface_len;
};