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I have several questions regarding these two specifications. Will appreciate if you clarify the current situation.

1. Is the new Multiboot 2 specification substantially better than the old one?
2. Will the old one become deprecated and unsupported?
3. Does the new one offer more hardware information or capabilities?
4. Do recent GRUB2 versions fully conform to Multiboot 2?
5. Which one of the two should be chosen for a new project?

Thanks.

ababo wrote:1. Is the new Multiboot 2 specification substantially better than the old one?

I would say it's an improvement. It's extensible, aims to add support for multiple architectures, more types of firmware ((U)EFI, so far), to provide more useful memory maps, access to more system information (in particular, SMBIOS and ACPI tables), DHCP, etc. Unfortunately, even if it's an improvement from Multiboot, Multiboot 2 is far from complete and not actively being worked on.

ababo wrote:2. Will the old one become deprecated and unsupported?

Both can be supported by boot loaders and kernels alike, as they have different magic numbers (Multiboot's signatures).

ababo wrote:3. Does the new one offer more hardware information or capabilities?

Yes. See the answer to question 1.

ababo wrote:4. Do recent GRUB2 versions fully conform to Multiboot 2?

Almost certainly. However, the PDF you probably came across is old. The latest revision can be found in a separate branch.

ababo wrote:5. Which one of the two should be chosen for a new project?

See the answer to question 2.

The original Multiboot specification has at least one very stupid design problem.
Multiboot is supposedly designed to allow your operating system to start in 32 bit protected mode.
But the disk information passed to the OS has the BIOS identifier. Stupid stupid stupid.

IMHO for BIOS PCs, any "multiboot" specification is pointless.
If your operating system has any success, most PCs will be running Windows and we all know that doesn't support the standard.

And I am sure you would be aware of the UEFI standard - It seems to already have multi os support built in.

I think you are missing the point of Multiboot, which is to allow sharing of both conformant bootloaders across conformant kernels and vice versa. For example, most people in this community don't want to bother writing boot loaders so Multiboot enables them to work directly on the kernel, focusing on whatever actually interests them.

Also, I have no idea why you mentioned BIOS and (U)EFI. Neither are a boot loaders.

Thank you.