Some Intel Tiger Lake-UP3/UP4 CPU models (TGL, family 6, model 140, stepping 1)
have reports of system hangs when a microcode update, that is included
since microcode-20201110 update, is applied[1].  In order to address this,
microcode update has been disabled by default on these systems.

[1] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/44

For the reference, SHA1 checksums of 06-8c-01 microcode files containing
microcode revisions in question are listed below:
 * 06-8c-01, revision 0x68: 2204a6dee1688980cd228268fdf4b6ed5904fe04
 * 06-8c-01, revision 0x88: 61b6590feb2769046d5b0c394179beaf2df51290

Please contact your system vendor for a BIOS/firmware update that contains
the latest microcode version.

The information regarding enforcing microcode update is provided below.

To enforce usage of the latest 06-8c-01 microcode revision for a specific kernel
version, please create a file "force-intel-06-8c-01" inside
/lib/firmware/<kernel_version> directory, run
"/usr/libexec/microcode_ctl/update_ucode" to add it to firmware directory
where microcode will be available for late microcode update, and run
"dracut -f --kver <kernel_version>", so initramfs for this kernel version
is regenerated and the microcode can be loaded early, for example:

    touch /lib/firmware/3.10.0-862.9.1/force-intel-06-8c-01
    /usr/libexec/microcode_ctl/update_ucode
    dracut -f --kver 3.10.0-862.9.1

After that, it is possible to perform a late microcode update by executing
"/usr/libexec/microcode_ctl/reload_microcode" or by writing value "1" to
"/sys/devices/system/cpu/microcode/reload" directly.

To enforce addition of this microcode for all kernels, please create file
"/etc/microcode_ctl/ucode_with_caveats/force-intel-06-8c-01", run
"/usr/libexec/microcode_ctl/update_ucode" for enabling late microcode updates,
and "dracut -f --regenerate-all" for enabling early microcode updates:

    mkdir -p /etc/microcode_ctl/ucode_with_caveats
    touch /etc/microcode_ctl/ucode_with_caveats/force-intel-06-8c-01
    /usr/libexec/microcode_ctl/update_ucode
    dracut -f --regenerate-all

Please refer to /usr/share/doc/microcode_ctl/README.caveats for additional
information.