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Implement a Multiboot-Compliant Bootloader Header

hard7/8

Parse and Load an ELF Binary from Disk Switch VGA Video Modes in Real Mode

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Compiler

2.0s Limit 256MB

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Implementation

Implement a Multiboot-compliant kernel header and info parser.

Requirements:

Define Multiboot header with magic, flags, and checksum
Calculate correct checksum: -(magic + flags)
Define multiboot info structure fields
Implement a parser that reads multiboot info
Print flags indicating available information
Print lower and upper memory sizes
Print boot device information
Print bootloader name
Verify EAX contains 0x2BADB002 on entry
Show how GRUB sets up the environment

Test:

Show Multiboot header with valid checksum
Show info structure parsed
Show memory sizes
Show flags indicating available features

Why This Matters

This is the exact header format GRUB scans for in the first 8192 bytes of a kernel image, and it's why hobby kernels (including nearly every OSDev-wiki 'Bare Bones' tutorial kernel) can boot under real GRUB without writing any disk-reading code at all. A wrong checksum here — magic + flags + checksum must sum to zero — is the single most common reason a Multiboot kernel refuses to boot under GRUB.

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Validation Suite

main.c

Workspace 1.0

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