acpi: Document ACPI tables and ELF files handling

[Zildj1an]

Document ACPI tables structs and code, including function usage examples. This is related to issue #74 titled "Document COCONUT-SVSM". Also document ELF files handling

[cclaudio]

When applicable, I think the two things below can be useful for people that need to work on this file:

• a comment at the top describing what spec we used in the file (e.g. Name, version)
• a comment in the structure indicating the table number in the spec it refers to

[Zildj1an]

Regarding @cclaudio comment, what do you think @joergroedel ? Should we link to any specific ACPI documentation?

[joergroedel]

Good question, for now the ACPI table definitions we actually use are there for decades, so I don't see much added value by adding version comments/links. The question is whether we will need to support features from more recent ACPI versions, in that case it would make sense to add this information, and also have it at the old tables for consistency.

[Zildj1an]

Thanks @joergroedel in that case I'm satisfied with the current state of the commit. I fixed a merge issue and that's the reason why we have a merge commit without my signature.

[Zildj1an]

I just updated this pull request, now we also document ELF files handling (see new commit) I will not continue documenting until this is merged to avoid bottleneck

[00xc]

Thanks @joergroedel in that case I'm satisfied with the current state of the commit. I fixed a merge issue and that's the reason why we have a merge commit without my signature.

I think this could be fixed by rebasing instead, no? We don't have guidelines on merges vs rebases for the project so this is fine for me, just mentioning it.

[00xc]

There's a missing closing backtick here. cargo doc will warn about it:

warning: could not parse code block as Rust code
   --> src/elf/mod.rs:398:9
    |
398 |       /// ```rust
    |  _________^
399 | |     /// use your_module::Elf64File;
400 | |     ///
401 | |     /// let elf_file = Elf64File::read(&elf_file_buf).unwrap();
402 | |     /// ``
    | |__________^
    |
    = note: error from rustc: unknown start of token: `
    = note: `#[warn(rustdoc::invalid_rust_codeblocks)]` on by default

[00xc]

The doctests for this PR are broken at the moment. Moreover, existing doctests in the main branch are also broken, so I suggest we fix those before merging these. I've opened #93 for this purpose.

You can run the doctests via cargo test --target=x86_64-unknown-linux-gnu --doc.

[Zildj1an]

Thanks @00xc I will reopen this PR without the issues mentioned.