Re: [PATCH v11 1/4] rust: io: add resource abstraction

[Danilo Krummrich <dakr@kernel.org>]

> +#[cfg(CONFIG_HAS_IOPORT)]
> +/// Returns a reference to the global `ioport_resource` variable.
> +pub fn ioport_resource() -> &'static Resource {
> +    // SAFETY: `bindings::ioport_resoure` has global lifetime and is of type Resource.
> +    unsafe { Resource::as_ref(&raw mut bindings::ioport_resource) }
> +}
> +
> +#[cfg(CONFIG_HAS_IOMEM)]
> +/// Returns a reference to the global `iomem_resource` variable.
> +pub fn iomem_resource() -> &'static Resource {
> +    // SAFETY: `bindings::iomem_resoure` has global lifetime and is of type Resource.
> +    unsafe { Resource::as_ref(&raw mut bindings::iomem_resource) }
> +}

This caught my attention, and I have a few questions:

   1) What do you need them for? I don't see any methods that would usually
      consume those.

   2) Why are they behind CONFIG_HAS_IOPORT and CONFIG_HAS_IOMEM, even though the
      C instances are not?

   3) What happens if we pass them to IoMem::new()? Is this really safe, or do we
      need them to be a special Resource type?