In the context of the recent Skylake/Kaby Lake hyper-threading bug , an
update of the intel microcode seems to be quite relevant. The resulting
package will contain "/boot/intel-ucode.img", which needs to be added as
first initial ram drive. This is achieved in extlinux by chaining the line
See  for more details. If this packet is accepted, changing
/sbin/update-extlinux to check for "/boot/init-ucode.img" and adding it
as first INITRD on detection seems to be a good idea.
All credit goes to Thomas Bächler , from whom I shamelessly stole the build