RFC

In the current PR I just advanced the compatibility bound to the next kernel major version. This means the package upgrade will break at the user side when that kernel becomes the default on their machine. In the PRs before, I removed the upper compatibility check with every upgrade, so that it fails loud and early with the appearance of a new kernel, long before it becomes the default on end user machines.

Which is the better way to do things? Failing early can be an annoyance, too, because openafs normally needs some weeks (even months) to become compatible with the latest kernel release.

For zfs we usually have no the upper bound if there is no known incompatibility and set it as build errors appear. This means in nixos unstable we sometimes propagate build errors to the users, if we are not marking incompatibilities fast enough. Not sure if it is the best approach. I suppose when somebody actively test the latest kernel with a third-party modules then disabling newer kernels proactively is better because the maintainer would test it before. When we do not have such a maintainer not having the upper bound is better because then the build errors become also apparent in hydra and we can fix it before a release.

I will update the PR, then, to not specify an upper bound and follow this approach when there is no known incompatibility at the time of the update.

Somehow we ended up with a openafs reference of a broken version in the manual.

The error comes from the nixos client module in nixos/modules/services/network-filesystems/openafs/client.nix:

module = mkOption {
          default = config.boot.kernelPackages.openafs;
          type = types.package;
          description = "OpenAFS kernel module package. MUST match the userland package!";
        };

nix-instantiate does not like the default assignment anymore. Replacing the package name with null fixes this particular issue but destroys the semantics...

I think there is also defaultText which is used instead of default so it will not evaluate openafs on aarch64.

backport: cb996fd