On 11.04.25 12:35 PM, Danilo Krummrich wrote:
On Fri, Apr 11, 2025 at 09:14:48AM +0200, Christian Schrefl wrote:
When trying to build the rust firmware abstractions on 32 bit arm the following build error occures:
error[E0308]: mismatched types --> rust/kernel/firmware.rs:20:14 | 20 | Self(bindings::request_firmware) | ---- ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected fn pointer, found fn item | | | arguments to this function are incorrect | = note: expected fn pointer `unsafe extern "C" fn(_, *const i8, _) -> _` found fn item `unsafe extern "C" fn(_, *const u8, _) -> _ {request_firmware}`This looks like you have local changes in your tree, running in this error. I get the exact same errors when I apply the following diff:
diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs index f04b058b09b2..a67047e3aa6b 100644 --- a/rust/kernel/firmware.rs +++ b/rust/kernel/firmware.rs @@ -12,7 +12,7 @@ /// One of the following: `bindings::request_firmware`, `bindings::firmware_request_nowarn`, /// `bindings::firmware_request_platform`, `bindings::request_firmware_direct`. struct FwFunc(
- unsafe extern "C" fn(*mut *const bindings::firmware, *const u8, *mut bindings::device) -> i32,
- unsafe extern "C" fn(*mut *const bindings::firmware, *const i8, *mut bindings::device) -> i32,
);
note: tuple struct defined here --> rust/kernel/firmware.rs:14:8 | 14 | struct FwFunc( | ^^^^^^
error[E0308]: mismatched types --> rust/kernel/firmware.rs:24:14 | 24 | Self(bindings::firmware_request_nowarn) | ---- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected fn pointer, found fn item | | | arguments to this function are incorrect | = note: expected fn pointer `unsafe extern "C" fn(_, *const i8, _) -> _` found fn item `unsafe extern "C" fn(_, *const u8, _) -> _ {firmware_request_nowarn}` note: tuple struct defined here --> rust/kernel/firmware.rs:14:8 | 14 | struct FwFunc( | ^^^^^^
error[E0308]: mismatched types --> rust/kernel/firmware.rs:64:45 | 64 | let ret = unsafe { func.0(pfw as _, name.as_char_ptr(), dev.as_raw()) }; | ------ ^^^^^^^^^^^^^^^^^^ expected `*const i8`, found `*const u8` | | | arguments to this function are incorrect | = note: expected raw pointer `*const i8` found raw pointer `*const u8`
error: aborting due to 3 previous errors
I did a test build with multi_v7_defconfig and I can't reproduce this issue.
Interesting, I've it seems this is only an issue on 6.13 with my arm patches applied.
It seems that it works on v6.14 and v6.15-rc1 but the error occurs on ffd294d346d1 (tag: v6.13) with my 32-bit arm patches applied.
I think the kernel does always use -funsigned-char, as also documented in commit 1bae8729e50a ("rust: map `long` to `isize` and `char` to `u8`")?
To fix this error the char pointer type in `FwFunc` is converted to `ffi::c_char`.
Fixes: de6582833db0 ("rust: add firmware abstractions") Cc: stable@vger.kernel.org # Backport only to 6.15 needed
Signed-off-by: Christian Schrefl chrisi.schrefl@gmail.com
rust/kernel/firmware.rs | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs index f04b058b09b2d2397e26344d0e055b3aa5061432..1d6284316f2a4652ef3f76272670e5e29b0ff924 100644 --- a/rust/kernel/firmware.rs +++ b/rust/kernel/firmware.rs @@ -5,14 +5,18 @@ //! C header: [`include/linux/firmware.h`](srctree/include/linux/firmware.h) use crate::{bindings, device::Device, error::Error, error::Result, str::CStr}; -use core::ptr::NonNull; +use core::{ffi, ptr::NonNull};
The change itself seems to be fine anyways, but I think we should use crate::ffi instead.
Right, I just did what RA recommended without thinking about it much.
I guess this patch isn't really needed. Should I still send a V2 using `crate::ffi`?
Cheers, Christian