https://www.gnu.org/software/grub/manual/multiboot/multiboot.txt
+-------------------+
0 | flags | (required)
+-------------------+
4 | mem_lower | (present if flags[0] is set)
8 | mem_upper | (present if flags[0] is set)
+-------------------+
12 | boot_device | (present if flags[1] is set)
+-------------------+
16 | cmdline | (present if flags[2] is set)
+-------------------+
20 | mods_count | (present if flags[3] is set)
24 | mods_addr | (present if flags[3] is set)
+-------------------+
28 - 40 | syms | (present if flags[4] or
| | flags[5] is set)
+-------------------+
44 | mmap_length | (present if flags[6] is set)
48 | mmap_addr | (present if flags[6] is set)
+-------------------+
52 | drives_length | (present if flags[7] is set)
56 | drives_addr | (present if flags[7] is set)
+-------------------+
60 | config_table | (present if flags[8] is set)
+-------------------+
64 | boot_loader_name | (present if flags[9] is set)
+-------------------+
68 | apm_table | (present if flags[10] is set)
+-------------------+
72 | vbe_control_info | (present if flags[11] is set)
76 | vbe_mode_info |
80 | vbe_mode |
82 | vbe_interface_seg |
84 | vbe_interface_off |
86 | vbe_interface_len |
+-------------------+
88 | framebuffer_addr | (present if flags[12] is set)
96 | framebuffer_pitch |
100 | framebuffer_width |
104 | framebuffer_height|
108 | framebuffer_bpp |
109 | framebuffer_type |
110-115 | color_info |
+-------------------+