Code review comment for lp://staging/~dannf/maas-images/lp1702976

fwiw, the code that landed here is weird.

config_addl_modules writes a file using 'cat <<EOF'
since 'EOF' is not quoted, we get shell expansion of '$' when writing

so.. what ends up getting written is:

case arm64 in
  arm*) copy_modules_dir ....
esac

which really I suspect we wanted to either
a.) only *write* the 'copy_modules_dir' into the file if the arch was arm*
b.) evaluate the arch at execution time (of mkinitramfs-tools).