On Sat, 21 Oct 2023 13:35:57 +0000
Benno Lossin [off-list ref] wrote:

quoted

Currently, it needs &'static DriverVTable
array so it works.

That is actually also incorrect. As the C side is going to modify
the `DriverVTable`, you should actually use `&'static mut DriverVTable`.
But since it is not allowed to be moved you have to use
`Pin<&'static mut DriverVTable>`.

I updated Registration::register(). Needs to add comments on requirement?

impl Registration {
    /// Registers a PHY driver.
    pub fn register(
        module: &'static crate::ThisModule,
        drivers: Pin<&'static mut [DriverVTable]>,
    ) -> Result<Self> {
        // SAFETY: The type invariants of [`DriverVTable`] ensure that all elements of the `drivers` slice
        // are initialized properly. So an FFI call with a valid pointer.
        to_result(unsafe {
            bindings::phy_drivers_register(drivers[0].0.get(), drivers.len().try_into()?, module.0)
        })?;
        // INVARIANT: The `drivers` slice is successfully registered to the kernel via `phy_drivers_register`.
        Ok(Registration { drivers })
    }
}

quoted

The C side uses static allocation too. If someone asks for, we could
loosen the restriction with a complicated implentation. But I doubt
that someone would ask for such.

With Wedson's patch you also would be using the static allocation
from `module!`. What my problem is, is that you are using a `static mut`
which is `unsafe` and you do not actually have to use it (with
Wedson's patch of course).

Like your vtable patch, I improve the code when something useful is
available.