Re: ABI mismatch build error for 6.17.y and rustc 1.91.0

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Nov 04, 2025 at 04:10:29PM +0100, Miguel Ojeda wrote:
> On Tue, Nov 4, 2025 at 3:26 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > Hm, that's a mix of gcc and rustc, does that
> > even work?
> 
> It "works" -- it is a best-effort hack as we always warn, but some
> distributions do use it.
> 
> GCC being used is unrelated to this issue though.
> 
> > The full .config can be found here:
> >         https://github.com/gregkh/gregkh-linux/blob/master/stable/configs/6.17.y
> 
> I picked this one and run it in v6.18-rc4, and I see the issue as expected:
> 
>     git clean -xdf
>     git checkout v6.18-rc4
>     curl -o .config
> https://raw.githubusercontent.com/gregkh/gregkh-linux/refs/heads/master/stable/configs/6.17.y
>     make olddefconfig
>     make
> 
> What is the config where you do not see the issue (after it gets
> sync'd, not before the build), i.e. the one for 6.18 that does not
> fail your build?
> 
> > The issue only started showing up when I moved rustc from 1.90.0 to
> > 1.91.0, nothing else changed on my system that I can determine.
> 
> Yes, the issue starts with Rust 1.91.0, so that is expected.
> 
> > Cool, what's the git id?  I'll be glad to try it.
> 
> It is the one from the rust-fixes branch:
> 
>     fad472efab0a805dd939f017c5b8669a786a4bcf
> 
> It is the top one in the rust-fixes branch at either:
> 
>     https://github.com/Rust-for-Linux/linux.git rust-fixes
>     https://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux.git rust-fixes
> 
> (Dirk gave the parent commit of that one, but in your case you need
> the top one too)

This is now fixed up with the patches tagged for stable, thanks, and
sorry for the noise, I didn't know it was already queued up.

greg k-h