Re: warning: unknown and unstable feature specified for `-Ctarget-feature`: `mma`

[Philip Li]

On Fri, Sep 18, 2026 at 11:12:13AM +0530, Mukesh Kumar Chaurasiya wrote:
> On Thu, Sep 17, 2026 at 03:38:46PM +0200, kernel test robot wrote:
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head:   238650ef6c7c7cca08e032527329424c9fbd70e5
> > commit: bc87cbdb952e9223616b839d64bdb4723aa2ed1d powerpc: Enable Rust for ppc64le
> > date:   7 weeks ago
> > config: powerpc64-randconfig-r2201-20260917 (https://download.01.org/0day-ci/archive/20260917/202609171549.xeqQabC6-lkp@xxxxxxxxx/config)
> > compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
> > rustc: rustc 1.96.0 (ac68faa20 2026-05-25)
> > smatch: v0.5.0-9187-g5189e3fb
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260917/202609171549.xeqQabC6-lkp@xxxxxxxxx/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Fixes: bc87cbdb952e ("powerpc: Enable Rust for ppc64le")
> > | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202609171549.xeqQabC6-lkp@xxxxxxxxx/
> > 
> > All warnings (new ones prefixed by >>):
> > 
> > >> 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
> > 
> > --
> > 0-DAY CI Kernel Test Service
> > https://github.com/intel/lkp-tests/wiki
> 
> This is expected, the issue for the same is raised to rust-lang.

Thanks for the info, I will configure the bot to avoid reporting this again.

> 
> Regards,
> Mukesh
>