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3.1.1 The layout of Multiboot header

The layout of the Multiboot header must be as follows:

Offset Type Field Name Note
0 u32 magic required
4 u32 flags required
8 u32 checksum required
12 u32 header_addr if flags[16] is set
16 u32 load_addr if flags[16] is set
20 u32 load_end_addr if flags[16] is set
24 u32 bss_end_addr if flags[16] is set
28 u32 entry_addr if flags[16] is set
32 u32 mode_type if flags[2] is set
36 u32 width if flags[2] is set
40 u32 height if flags[2] is set
44 u32 depth if flags[2] is set

The fields ‘magic’, ‘flags’ and ‘checksum’ are defined in Header magic fields, the fields ‘header_addr’, ‘load_addr’, ‘load_end_addr’, ‘bss_end_addr’ and ‘entry_addr’ are defined in Header address fields, and the fields ‘mode_type’, ‘width’, ‘height’ and ‘depth’ are defined in Header graphics fields.