ARM kernels are compressed with gzip, but most versions of ipxe cannot handle this (it's not clear what happens with raw pxe). See https://github.com/coreos/fedora-coreos-tracker/issues/1019 for more info.

If the platform is aarch64 we'll need to decompress the kernel like we do in https://github.com/openshift/machine-os-images/commit/1ed36d657fa3db55fc649761275c1f89cd7e8abe