Re: Failure to build with LLVM for the Wii

[Nathan Chancellor <nathan@kernel.org>]

Hi Aelin,

On Wed, Feb 25, 2026 at 12:30:30AM +0100, Aelin wrote:
> On 1/29/26 11:31 PM, Nathan Chancellor wrote:
> > Hi Link,
> > 
> > On Thu, Jan 29, 2026 at 11:55:46AM +0100, Link Mauve wrote:
> > > I’m trying to build the kernel for the Nintendo Wii, using LLVM instead
> > > of gcc, in order to bring Rust support to this architecture (and also
> > > because my distribution doesn’t ship a cross-compiling gcc), but I get
> > > this build issue near the end:
> > > ```
> > > % make O=wii LLVM=1 ARCH=powerpc -j1
> > > make[1]: Entering directory '/home/linkmauve/dev/linux/wii'
> > >    GEN     Makefile
> > >    CALL    ../scripts/checksyscalls.sh
> > >    DESCEND objtool
> > >    INSTALL libsubcmd_headers
> > >    WRAP    arch/powerpc/boot/dtbImage.wii
> > > objcopy: Unable to recognise the format of the input file `vmlinux'
> > > make[3]: *** [../arch/powerpc/boot/Makefile:394: arch/powerpc/boot/dtbImage.wii] Error 1
> > > make[2]: *** [../arch/powerpc/Makefile:236: zImage] Error 2
> > > make[1]: *** [/home/linkmauve/dev/linux/Makefile:248: __sub-make] Error 2
> > > make[1]: Leaving directory '/home/linkmauve/dev/linux/wii'
> > > make: *** [Makefile:248: __sub-make] Error 2
> > > ```
> > > 
> > > I believe it should use $(OBJCOPY) instead of objcopy, which is set to
> > > llvm-objcopy, but couldn’t figure out where it is misconfigured.
> > > 
> > > Thanks for your help!
> > 
> > It is the arch/powerpc/boot/wrapper script:
> > 
> >    https://github.com/ClangBuiltLinux/linux/issues/1601
> > 
> > I have a WIP series from long ago that may be a good starting point for
> > getting something working but there were some errors I never got around
> > to solving before having to shelve it for other issues:
> > 
> >    https://git.kernel.org/pub/scm/linux/kernel/git/nathan/linux.git/log/?h=wip/llvm-1-powerpc-boot-wrapper
> > 
> > Maybe something I (or someone else) can get back to soon.
> > 
> > Cheers,
> > Nathan
> > 
> 
> Hi Nathan,
> 
> your last 3 patches on this branch do indeed fix the wrapper script for the
> cross-compilation with LLVM=1 ARCH=powerpc without CROSS_COMPILE set or GNU
> binutils in PATH. They look good to me! Would you be willing to submit them
> now without touching the VDSO? That part does not seem to be necessary to
> fix the wrapper script for this usecase, so it should strictly be an
> improvement. I'd also be happy to pick up your patches, send them and
> follow-up on feedback if you don't want to do it yourself.

Thanks a lot for testing. For the record, I submitted the vDSO parts
separately and it landed as

  4406b12214f6 ("powerpc/vdso: Link with ld.lld when requested")

so it can safely be ignored altogether.

I am a little busy with things at the moment so I am not sure how soon I
will be able to pick this up. I am more than happy to let you take over
from here if you have the time and energy to get it tested and
submitted now. You can either take full authorship or stick a
Co-developed-by on it, does not matter to me.

Cheers,
Nathan