building csky with CC=clang

building csky with CC=clang

[Nick Desaulniers]

Hello!
I was playing with some of LLVM's experimental backends (m68k) and saw
there was a CSKY backend. I rebuilt LLVM to support CSKY, but I ran
into trouble building the kernel before even getting to the compiler
invocation:

$ ARCH=csky CROSS_COMPILE=csky-linux-gnu- make CC=clang -j71 defconfig
...
scripts/Kconfig.include:40: linker 'csky-linux-gnu-ld' not found

My distro doesn't package binutils-csky-linux-gnu, is there
documentation on how to build the kernel targeting CSKY, starting with
building GNU binutils configured with CSKY emulation?
-- 
Thanks,
~Nick Desaulniers

Re: building csky with CC=clang

[Fangrui Song]

On 2020-12-22, 'Nick Desaulniers' via Clang Built Linux wrote:
>Hello!
>I was playing with some of LLVM's experimental backends (m68k) and saw
>there was a CSKY backend. I rebuilt LLVM to support CSKY, but I ran
>into trouble building the kernel before even getting to the compiler
>invocation:
>
>$ ARCH=csky CROSS_COMPILE=csky-linux-gnu- make CC=clang -j71 defconfig
>...
>scripts/Kconfig.include:40: linker 'csky-linux-gnu-ld' not found
>
>My distro doesn't package binutils-csky-linux-gnu, is there
>documentation on how to build the kernel targeting CSKY, starting with
>building GNU binutils configured with CSKY emulation?

Note also that the llvm/lib/Target/CSKY has not been fully upstreamed
yet. It is a WIP https://lists.llvm.org/pipermail/llvm-dev/2020-August/144481.html
I will not expect clang csky to work currently.
(The latest committed LLVM patch is https://reviews.llvm.org/D93372
Normally committing an important piece of a large patch series like this should take
a bit longer time longer after someone in the community accepted it
https://llvm.org/docs/CodeReview.html#can-code-be-reviewed-after-it-is-committed )

I do want to raise the recent LLVM M68k target. Its patches ([M67k] (Patch */8))
are very organized and the main proposer shares updates to llvm-dev regularly.
There is a lot from the process where the C-SKY target can learn from.