Backporting 6.2 kernel to Jammy causes config issues at build time

[Andrea Righi]

On Mon, Apr 24, 2023 at 01:36:33PM -0600, Tim Gardner wrote:
> Hi Andrea,
> 
> I've been working on backporting the Lunar Azure kernel to Jammy [1]. For
> some reason the RUST annotations that I've specified are ignored when I
> upload sources to CBD or Launchpad. See attached log file.
> 
> I can otherwise run 'cranky updateconfigs -c' with no error.
> 
> Since you architected this new method for managing configs, I wondered if
> you had any thoughts ?

So, ...

> ***
> *** Rust compiler 'rustc-1.62' is too new. This may or may not work.
> ***   Your version:     1.62.1
> ***   Expected version: 1.62.0
> ***
> Rust is available!

^ This tells you this build environment (jammy build chroot in cbd) has
all the components that are required to enable Rust (basically toolchain
requirements are satisfied).

So, this means that you *can* enable Rust if you want.

> check-config: loading annotations from /build/jammy/debian.azure-6.2/config/annotations
> check-config: FAIL: (y != -): CONFIG_RUST_IS_AVAILABLE policy<{'amd64': '-', 'arm64': '-', 'armhf': '-', 'ppc64el': '-', 'riscv64': '-', 's390x': '-'}>)

^ This tells you that the expected value for CONFIG_RUST_IS_AVAILABLE
was '-', but instead it's 'y'.

I read this as: your local build chroot doesn't have all the components
required by Rust, while cbd has them (need to refresh your local chroot
maybe? or maybe we have not installed rustc-1.62, bindgen-0.56, etc. in
our jammy build chroot?).

Moreover, I think we don't want Rust enabled in jammy, so CONFIG_RUST
should be not set, but CONFIG_RUST_IS_AVAILABLE should be 'y', because
theoretically we already have all the required components in Jammy.

-Andrea