Re: [PATCH V17 0/7] Rust Support for powerpc

[Nathan Chancellor <nathan@kernel.org>]

On Tue, Aug 04, 2026 at 12:11:57PM +0200, Link Mauve wrote:
> Hi,
> 
> On Mon, Aug 03, 2026 at 12:27:13PM +0530, Madhavan Srinivasan wrote:
> > On Wed, 08 Jul 2026 13:54:47 +0530, Mukesh Kumar Chaurasiya (IBM) wrote:
> > > Enable experimental rust support for ppc64le and ppc32be. The patch for
> > > ppc32 has been provided by Link Mauve[1] and ppc64le support[2] has been
> > > merged over it. ppc32 needs some toolchain fixes mentioned in the patch
> > > `rust: Add PowerPC support` and the discussion for that is done here[1].
> > > 
> > > This has been tested on
> > > - powernv9 hardware
> > > - pseries P11 hardware
> > > - pseries(9, 10) qemu
> > > - powernv(9, 10) qemu
> > > - rustdoc on x86 and powerpc64le
> > > - rusttest on x86 and powerpc64le
> > > 
> > > [...]
> > 
> > Applied to powerpc/next.
> > 
> > [1/7] rust: Fix "multiple candidates for rmeta dependency core" error
> >       https://git.kernel.org/powerpc/c/00cdfd072c709c608606461d7d44d4613119bfa9
> > [2/7] dma-resv: Fix undefined symbol when CONFIG_DMA_SHARED_BUFFER is disabled
> >       https://git.kernel.org/powerpc/c/be809b60cbb61aab96179f44ac3670242ae72996
> > [3/7] powerpc/jump_label: adjust inline asm to be consistent
> >       https://git.kernel.org/powerpc/c/13244c0a40139fe66c4c5c5655f4d732a6002957
> > [4/7] rust/powerpc: Set min rustc version for powerpc
> >       https://git.kernel.org/powerpc/c/e299147cdc8e19c6421a6b7863dc82a35b09d967
> > [5/7] rust: Make __udivdi3() and __umoddi3() panic
> >       https://git.kernel.org/powerpc/c/c93c194e4ee71a734986fd99a8b1ec9fbb7a9b8b
> > [6/7] rust: Add PowerPC support
> >       https://git.kernel.org/powerpc/c/73b741adb264967093ef4eb59905618a7e0d0de0
> > [7/7] powerpc: Enable Rust for ppc64le
> >       https://git.kernel.org/powerpc/c/bc87cbdb952e9223616b839d64bdb4723aa2ed1d
> > 
> > cheers
> > 
> 
> I just tested those again in linux-next, with the Wii support series on
> top, but now the kernel fails to build due to ARCH_WARN_ASM and
> ARCH_WARN_REACHABLE not being defined on PowerPC:

I also see the following warnings (in addition to that error):

  warning: unknown and unstable feature specified for `-Ctarget-feature`: `mma`
    |
    = note: it is still passed through to the codegen backend, but use of this feature might be unsound and the behavior of this feature can change in the future
    = help: consider filing a feature request

  warning: unstable feature specified for `-Ctarget-feature`: `vsx`
    |
    = note: this feature is not stably supported; its behavior can change in the future

  warning: unknown and unstable feature specified for `-Ctarget-feature`: `hard-float`
    |
    = note: it is still passed through to the codegen backend, but use of this feature might be unsound and the behavior of this feature can change in the future
    = help: consider filing a feature request

  warning: unstable feature specified for `-Ctarget-feature`: `altivec`
    |
    = note: this feature is not stably supported; its behavior can change in the future

  clang diag: arch/powerpc/include/uapi/asm/ioctl.h:5:9: warning: '_IOC_SIZEBITS' macro redefined [-Wmacro-redefined]
  clang diag: arch/powerpc/include/uapi/asm/ioctl.h:6:9: warning: '_IOC_DIRBITS' macro redefined [-Wmacro-redefined]
  clang diag: arch/powerpc/include/uapi/asm/ioctl.h:8:9: warning: '_IOC_NONE' macro redefined [-Wmacro-redefined]
  clang diag: arch/powerpc/include/uapi/asm/ioctl.h:10:9: warning: '_IOC_WRITE' macro redefined [-Wmacro-redefined]
  warning: 4 warnings emitted

when building this series in next-20260804 with rustc 1.97.1. I am not
sure where the clang diagnostic warnings come from. I assume the target
feature warnings are expected but it would be good to get those
addressed sooner rather than later. I see '-hard-float' has an issue
open

  https://github.com/rust-lang/rust/issues/117347

but I don't think I see issues open for the other ones.

-- 
Cheers,
Nathan