const fn gdt creation

[tepperson2]

I would like the ability to create a GlobalDescriptorTable with a const fn. I am writing a kernel and need to ensure that no 64-bit code runs before I jump to long mode because the kernel is started in 32-bit mode. I want to define the gdt structure with rust.

[tepperson2]

I just noticed the "const_fn" feature, but I would like to do this on stable rust.

[phil-opp]

The const_fn feature is using the compiler's unstable const_mut_refs feature, which is hopefully stabilized soon. See rust-lang/rust#57349 for the current state. Unfortunately, we don't have any other way to create a GDT in a const environment at the moment. If you have an idea how we could implement it, please let us know!

[tepperson2]

I added a pull request #406

[josephlr]

Note that you can also use GlobalDescriptorTable::from_raw_slice if you want something that works on the current version of stable Rust.