Support for multiboot2

[azenla]

This will be interesting! multiboot2 is a standard boot protocol that is common for custom bootable code, and is used in production for Xen on x86_64 often.

Adding support is likely to be non-trivial since this would potentially be the first non-EFI-assisted boot module.

[phip1611]

Multiboot2 knows a mode where boot services are active and the CPU is in 64-bit mode. You might can start with implementing only that, i.e. a subset of multiboot2. 🤔

[azenla]

Oh that's good to know! We could definitely do that!

Thanks @phip1611!

[phip1611]

Relevant pointers:

• spec: 3.5 EFI amd64 machine state with boot services enabled
• multiboot2 crate

As luck would have it, I'm also the maintainer of rust-osdev/multiboot2. So if you use the library and find something missing, I'd be happy to receive feedback and suggestions! Using the Builder should help you a lot, hopefully.

To be fair, I think the vast majority of multiboot2 kernels/payloads won't use the EFI AMD64 machine state with boot services enabled but much rather 3.3 I386 machine state