On Thu, Apr 17, 2025 at 03:26:14PM -0400, Tamir Duberstein wrote:
[...]
> >
> > > Ok(())
> > > }
> > > diff --git a/rust/kernel/device_id.rs b/rust/kernel/device_id.rs
> > > index e5859217a579..4063f09d76d9 100644
> > > --- a/rust/kernel/device_id.rs
> > > +++ b/rust/kernel/device_id.rs
> > > @@ -82,7 +82,7 @@ impl<T: RawDeviceId, U, const N: usize> IdArray<T, U,
> > > N> {
> > > unsafe {
> > > raw_ids[i]
> > > .as_mut_ptr()
> > > - .byte_offset(T::DRIVER_DATA_OFFSET as _)
> > > + .byte_add(T::DRIVER_DATA_OFFSET)
> > > .cast::<usize>()
> > > .write(i);
> > > }
> > > diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
> > > index f7e8f5f53622..70d12014e476 100644
> > > --- a/rust/kernel/devres.rs
> > > +++ b/rust/kernel/devres.rs
> > > @@ -45,7 +45,7 @@ struct DevresInner<T> {
> > > /// # Example
> > > ///
> > > /// ```no_run
> > > -/// # use kernel::{bindings, c_str, device::Device, devres::Devres,
> > > io::{Io, IoRaw}};
> > > +/// # use kernel::{bindings, c_str, device::Device, devres::Devres,
> > > ffi::c_void, io::{Io, IoRaw}};
> > > /// # use core::ops::Deref;
> > > ///
> > > /// // See also [`pci::Bar`] for a real example.
> > > @@ -59,19 +59,19 @@ struct DevresInner<T> {
> > > /// unsafe fn new(paddr: usize) -> Result<Self>{
> > > /// // SAFETY: By the safety requirements of this function
> > > [`paddr`, `paddr` + `SIZE`) is
> > > /// // valid for `ioremap`.
> > > -/// let addr = unsafe { bindings::ioremap(paddr as _, SIZE as _)
> > > };
> > > +/// let addr = unsafe { bindings::ioremap(paddr as
> > > bindings::phys_addr_t, SIZE) };
> >
> >
> > /// let addr = unsafe {
> > bindings::ioremap(bindings::phys_addr_t::from(paddr), SIZE) };
> >
> > better? Or even with .into()
> >
> > /// let addr = unsafe { bindings::ioremap(paddr.into(), SIZE) };
>
> This doesn't compile because `paddr` is usize, and
> `bindings::phys_addr_t` is u64 (on my machine, which is aarch64).
>
Ok, looks like Rust yet doesn't provide From/Into between usize and u64
even if the pointer size is fixed. Latest discussion can be found at:
https://github.com/rust-lang/rust/issues/41619#issuecomment-2056902943
Lemme see if we can get an issue tracking this. Thanks for taking a
look.
> > > /// if addr.is_null() {
> > > /// return Err(ENOMEM);
> > > /// }
> > > ///
> > > -/// Ok(IoMem(IoRaw::new(addr as _, SIZE)?))
> > > +/// Ok(IoMem(IoRaw::new(addr as usize, SIZE)?))
> > > /// }
> > > /// }
> > > ///
> > > /// impl<const SIZE: usize> Drop for IoMem<SIZE> {
> > > /// fn drop(&mut self) {
> > > /// // SAFETY: `self.0.addr()` is guaranteed to be properly
> > > mapped by `Self::new`.
> > > -/// unsafe { bindings::iounmap(self.0.addr() as _); };
> > > +/// unsafe { bindings::iounmap(self.0.addr() as *mut c_void); };
> > > /// }
> > > /// }
> > > ///
> > [...]
> > > diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs
> > > index 43ecf3c2e860..851a6339aa90 100644
> > > --- a/rust/kernel/dma.rs
> > > +++ b/rust/kernel/dma.rs
> > > @@ -38,7 +38,7 @@
> > > impl Attrs {
> > > /// Get the raw representation of this attribute.
> > > pub(crate) fn as_raw(self) -> crate::ffi::c_ulong {
> > > - self.0 as _
> > > + self.0 as crate::ffi::c_ulong
> >
> > crate::ffi::c_ulong::from(self.0)
> >
> > maybe, a C unsigned long should always be able to hold the whole `Attr`
> > and a lossly casting is what this function does.
>
> This also doesn't compile: "the trait `core::convert::From<u32>` is
> not implemented for `usize`". Upstream has ambitions of running on
> 16-bit, I guess :)
>
They do but they also have the target_pointer_width cfg, so they can
totally provide these functions. It's just they want to find a better
way (like the link I post above).
Regards,
Boqun
