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The existing use case where it represents a region of compile-tim= e >> known minimum size and run-time known actual size is moved to a custom >> dynamic-sized type `Region` instead. The `maxsize` method is also >> renamed to `size` to reflect that it is the actual size (not a bound) of >> the region. >> >> Signed-off-by: Gary Guo >> --- >> rust/kernel/devres.rs | 7 ++-- >> rust/kernel/io.rs | 84 +++++++++++++++++++++++++++++++++---------- >> rust/kernel/io/mem.rs | 4 +-- >> rust/kernel/pci/io.rs | 4 +-- >> 4 files changed, 74 insertions(+), 25 deletions(-) >> >> diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs >> index 9e5f93aed20c..65a4082122af 100644 >> --- a/rust/kernel/devres.rs >> +++ b/rust/kernel/devres.rs >> @@ -71,14 +71,15 @@ struct Inner { >> /// IoKnownSize, >> /// Mmio, >> /// MmioRaw, >> -/// PhysAddr, // >> +/// PhysAddr, >> +/// Region, // >> /// }, >> /// prelude::*, >> /// }; >> /// use core::ops::Deref; >> /// >> /// // See also [`pci::Bar`] for a real example. >> -/// struct IoMem(MmioRaw); >> +/// struct IoMem(MmioRaw>); >> /// >> /// impl IoMem { >> /// /// # Safety >> @@ -93,7 +94,7 @@ struct Inner { >> /// return Err(ENOMEM); >> /// } >> /// >> -/// Ok(IoMem(MmioRaw::new(addr as usize, SIZE)?)) >> +/// Ok(IoMem(MmioRaw::new_region(addr as usize, SIZE)?)) > > Should this be `addr.addr()` ? This (and other occurence) are all existing use of casts introduced probabl= y before we enabled strict provenance APIs. These should be fixed separately. > >> /// } >> /// } >> /// >> diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs >> index fcc7678fd9e3..d7f2145fa9b9 100644 >> --- a/rust/kernel/io.rs >> +++ b/rust/kernel/io.rs >> @@ -6,7 +6,8 @@ >> >> use crate::{ >> bindings, >> - prelude::*, // >> + prelude::*, >> + ptr::KnownSize, // >> }; >> >> pub mod mem; >> @@ -31,39 +32,85 @@ >> /// `CONFIG_PHYS_ADDR_T_64BIT`, and it can be a u64 even on 32-bit arch= itectures. >> pub type ResourceSize =3D bindings::resource_size_t; >> >> +/// Untyped I/O region. >> +/// >> +/// This type can be used when an I/O region without known type informa= tion has a compile-time known >> +/// minimum size (and a runtime known actual size). >> +/// >> +/// The `SIZE` generic parameter indicate the minimum size of the regio= n. >> +#[repr(transparent)] >> +pub struct Region { >> + inner: [u8], >> +} >> + >> +impl KnownSize for Region { >> + #[inline(always)] >> + fn size(p: *const Self) -> usize { >> + (p as *const [u8]).len() > > Is `as` the only way to cast fat pointers? Yes. There's no way currently stable way to guarantee a matching metadata w= ith traits. Best, Gary > >> + } >> +} >> +