Function install_kernel 

pub fn install_kernel(
    archive: &Path,
    expected: &str,
    cache: &Path,
) -> Result<Installed, CliError>

Check the kernel header tree’s artifact and install it where every Linux target reads it.

The same four steps as install, against the tree’s own record rather than a sysroot’s. What is not checked is that the tree is the release a sysroot’s kernel line names, for the reason rucc_sysroot::Kernel gives: the two are produced by two commands and can be paired either way, and the records are what make a stale pairing visible.

Errors

The same as install’s, with a record that is not a kernel tree’s in place of a sysroot for the wrong target.