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Date: Thu, 29 Jan 2026 15:31:36 -0700
From: Nathan Chancellor <nathan@kernel.org>
To: Link Mauve <linkmauve@linkmauve.fr>
Cc: linuxppc-dev@lists.ozlabs.org, llvm@lists.linux.dev
Subject: Re: Failure to build with LLVM for the Wii
Message-ID: <20260129223136.GA1614447@ax162>
References: <aXs8sgAcci9FKKpx@luna>
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In-Reply-To: <aXs8sgAcci9FKKpx@luna>

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