Mainline loongarch64 defconfig+Rust build error

Mainline loongarch64 defconfig+Rust build error

[Miguel Ojeda]

Hi all,

I am seeing in mainline loongarch64 defconfig+Rust the following build
error [1].

Cheers,
Miguel

[1]

 error[E0425]: cannot find value `compat_ptr_ioctl` in crate `bindings`
     --> drivers/android/binder/rust_binder_main.rs:317:38
      |
317   |         compat_ioctl: Some(bindings::compat_ptr_ioctl),
      |                                      ^^^^^^^^^^^^^^^^ help: a
function with a similar name exists: `compat_sys_ioctl`
      |
     ::: /__w/quick/quick/linux/rust/bindings/bindings_generated.rs:78264:5
      |
78264 |     pub fn compat_sys_ioctl(fd: ffi::c_uint, cmd: ffi::c_uint,
arg: compat_ulong_t) -> ffi::c_long;
      |     ----------------------------------------------------------------------------------------------
similarly named function `compat_sys_ioctl` defined here

Re: Mainline loongarch64 defconfig+Rust build error

[Xi Ruoyao]

On Tue, 2025-12-09 at 11:56 +0100, Miguel Ojeda wrote:
> Hi all,
> 
> I am seeing in mainline loongarch64 defconfig+Rust the following build
> error [1].
> 
> Cheers,
> Miguel
> 
> [1]
> 
>  error[E0425]: cannot find value `compat_ptr_ioctl` in crate `bindings`
>      --> drivers/android/binder/rust_binder_main.rs:317:38
>       |
> 317   |         compat_ioctl: Some(bindings::compat_ptr_ioctl),
>       |                                      ^^^^^^^^^^^^^^^^ help: a
> function with a similar name exists: `compat_sys_ioctl`
>       |
>      ::: /__w/quick/quick/linux/rust/bindings/bindings_generated.rs:78264:5
>       |
> 78264 |     pub fn compat_sys_ioctl(fd: ffi::c_uint, cmd: ffi::c_uint,
> arg: compat_ulong_t) -> ffi::c_long;
>       |     ----------------------------------------------------------------------------------------------
> similarly named function `compat_sys_ioctl` defined here

I highly doubt if this is really a LoongArch-only issue.  We have:

#ifdef CONFIG_COMPAT
extern long compat_ptr_ioctl(struct file *file, unsigned int cmd, 
                    unsigned long arg);
#else
#define compat_ptr_ioctl NULL
#endif

AFAIK bindgen does not translate C preprocessor macro definitions, so
when !CONFIG_COMPAT we won't have the Rust binding for it.

And as LA32 is not upstreamed it's pointless to support COMPAT for
LoongArch, yet.

-- 
Xi Ruoyao <xry111@xry111.site>

Re: Mainline loongarch64 defconfig+Rust build error

[Gary Guo]

On Tue, 09 Dec 2025 19:28:33 +0800
Xi Ruoyao <xry111@xry111.site> wrote:

> On Tue, 2025-12-09 at 11:56 +0100, Miguel Ojeda wrote:
> > Hi all,
> > 
> > I am seeing in mainline loongarch64 defconfig+Rust the following build
> > error [1].
> > 
> > Cheers,
> > Miguel
> > 
> > [1]
> > 
> >  error[E0425]: cannot find value `compat_ptr_ioctl` in crate `bindings`
> >      --> drivers/android/binder/rust_binder_main.rs:317:38
> >       |
> > 317   |         compat_ioctl: Some(bindings::compat_ptr_ioctl),
> >       |                                      ^^^^^^^^^^^^^^^^ help: a
> > function with a similar name exists: `compat_sys_ioctl`
> >       |
> >      ::: /__w/quick/quick/linux/rust/bindings/bindings_generated.rs:78264:5
> >       |
> > 78264 |     pub fn compat_sys_ioctl(fd: ffi::c_uint, cmd: ffi::c_uint,
> > arg: compat_ulong_t) -> ffi::c_long;
> >       |     ----------------------------------------------------------------------------------------------
> > similarly named function `compat_sys_ioctl` defined here  
> 
> I highly doubt if this is really a LoongArch-only issue.  We have:
> 
> #ifdef CONFIG_COMPAT
> extern long compat_ptr_ioctl(struct file *file, unsigned int cmd, 
>                     unsigned long arg);
> #else
> #define compat_ptr_ioctl NULL
> #endif
> 
> AFAIK bindgen does not translate C preprocessor macro definitions, so
> when !CONFIG_COMPAT we won't have the Rust binding for it.
> 
> And as LA32 is not upstreamed it's pointless to support COMPAT for
> LoongArch, yet.
> 

I think bindgen can't handle this on its own anyway, as it doesn't
really know that you want a `Option<fn(..) -> ...>` type here instead
of just a function item.

Probably the best way is for each user of this function handle
CFG_COMPAT on its own for now. Alternatively, we can just provide a
helper that just returns `-ENONIOCTLCMD` instead of using NULL?

Besat,
Gary

Re: Mainline loongarch64 defconfig+Rust build error

[hev]

On Tue, Dec 9, 2025 at 6:58 PM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> Hi all,
>
> I am seeing in mainline loongarch64 defconfig+Rust the following build
> error [1].
>
> Cheers,
> Miguel
>
> [1]
>
>  error[E0425]: cannot find value `compat_ptr_ioctl` in crate `bindings`
>      --> drivers/android/binder/rust_binder_main.rs:317:38
>       |
> 317   |         compat_ioctl: Some(bindings::compat_ptr_ioctl),

It looks like the rust binder driver also needs to handle
!CONFIG_COMPAT. Here's a reference for that:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/rust/kernel/miscdevice.rs?h=v6.18#n410

>       |                                      ^^^^^^^^^^^^^^^^ help: a
> function with a similar name exists: `compat_sys_ioctl`
>       |
>      ::: /__w/quick/quick/linux/rust/bindings/bindings_generated.rs:78264:5
>       |
> 78264 |     pub fn compat_sys_ioctl(fd: ffi::c_uint, cmd: ffi::c_uint,
> arg: compat_ulong_t) -> ffi::c_long;
>       |     ----------------------------------------------------------------------------------------------
> similarly named function `compat_sys_ioctl` defined here
>

--
hev

Re: Mainline loongarch64 defconfig+Rust build error

[Alice Ryhl]

On Tue, Dec 09, 2025 at 08:20:46PM +0800, hev wrote:
> On Tue, Dec 9, 2025 at 6:58 PM Miguel Ojeda
> <miguel.ojeda.sandonis@gmail.com> wrote:
> >
> > Hi all,
> >
> > I am seeing in mainline loongarch64 defconfig+Rust the following build
> > error [1].
> >
> > Cheers,
> > Miguel
> >
> > [1]
> >
> >  error[E0425]: cannot find value `compat_ptr_ioctl` in crate `bindings`
> >      --> drivers/android/binder/rust_binder_main.rs:317:38
> >       |
> > 317   |         compat_ioctl: Some(bindings::compat_ptr_ioctl),
> 
> It looks like the rust binder driver also needs to handle
> !CONFIG_COMPAT. Here's a reference for that:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/rust/kernel/miscdevice.rs?h=v6.18#n410

Yeah, it just needs a `#[cfg(CONFIG_COMPAT)] like miscdevice. Do you
want to add it? Otherwise I'll get to it soon.

Alice

Re: Mainline loongarch64 defconfig+Rust build error

[Alice Ryhl]

On Thu, Dec 11, 2025 at 10:24 AM Alice Ryhl <aliceryhl@google.com> wrote:
>
> On Tue, Dec 09, 2025 at 08:20:46PM +0800, hev wrote:
> > On Tue, Dec 9, 2025 at 6:58 PM Miguel Ojeda
> > <miguel.ojeda.sandonis@gmail.com> wrote:
> > >
> > > Hi all,
> > >
> > > I am seeing in mainline loongarch64 defconfig+Rust the following build
> > > error [1].
> > >
> > > Cheers,
> > > Miguel
> > >
> > > [1]
> > >
> > >  error[E0425]: cannot find value `compat_ptr_ioctl` in crate `bindings`
> > >      --> drivers/android/binder/rust_binder_main.rs:317:38
> > >       |
> > > 317   |         compat_ioctl: Some(bindings::compat_ptr_ioctl),
> >
> > It looks like the rust binder driver also needs to handle
> > !CONFIG_COMPAT. Here's a reference for that:
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/rust/kernel/miscdevice.rs?h=v6.18#n410
>
> Yeah, it just needs a `#[cfg(CONFIG_COMPAT)] like miscdevice. Do you
> want to add it? Otherwise I'll get to it soon.
Oh looks like there is already a patch for it.

Alice