Edit: /etc/default/intel-microcode (1029B)
# Configuration script for intel-microcode version 3
#
# initramfs helper
#
# Set this to "no" to disable automatic microcode updates on boot;
# Set this to "auto" to use early initramfs mode automatically (default);
# Set this to "early" to always attempt to create an early initramfs;
#IUCODE_TOOL_INITRAMFS=auto
# Set this to "yes" (default) to use "iucode_tool --scan-system" to reduce
# the initramfs size bloat, by detecting which Intel processors are active
# in this system, and installing only their microcodes.
#
# Set this to "no" to either include all microcodes, or only the microcodes
# selected through the use of IUCODE_TOOL_EXTRA_OPTIONS below.
#
# WARNING: including all microcodes will increase initramfs size greatly.
# This can cause boot issues if the initramfs is already large.
#IUCODE_TOOL_SCANCPUS=yes
# Extra options to pass to iucode_tool, useful to forbid or to
# force the inclusion of microcode for specific processor signatures.
# See iucode_tool(8) for details.
#IUCODE_TOOL_EXTRA_OPTIONS=""