FM / caveats

/usr/share/doc/microcode_ctl/caveats

Name	Size	Mode	Actions
06-2d-07_readme	2978	0644	edit dl rm
06-4e-03_readme	4731	0644	edit dl rm
06-4f-01_readme	3948	0644	edit dl rm
06-5e-03_readme	4779	0644	edit dl rm
06-8c-01_readme	3593	0644	edit dl rm
06-8e-9e-0x-0xca_readme	12547	0644	edit dl rm
06-8e-9e-0x-dell_readme	12535	0644	edit dl rm
06-8f-08_readme	2171	0644	edit dl rm
06-55-04_readme	5450	0644	edit dl rm
intel_readme	2461	0644	edit dl rm

Edit: /usr/share/doc/microcode_ctl/caveats/06-8f-08_readme (2171B)

For the reference, SHA1 checksums of 06-8f-08 microcode files containing
microcode revisions in question are listed below:
 * 06-8f-08, revision 0x2b0005c0: adf8b6aa2718ff16f3d19d34ec389270073d2b5e
 * 06-8f-08, revision 0x2b000603: 729014bd05dfb6593152ea7ee12330791bc22bec
 * 06-8f-08, revision 0x2b000620: e39812f7aff520c79f3f6fa013bd501781d92f8e
 * 06-8f-08, revision 0x2b000639: 39d91f7a962245ba79fea0611732c86efbd71bc5

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

The information regarding disabling microcode update is provided below.

To disable usage of the newer microcode revision for a specific kernel
version, please create a file "disallow-intel-06-8f-08" inside
/lib/firmware/<kernel_version> directory, run
"/usr/libexec/microcode_ctl/update_ucode" to update firmware directory
used for late microcode updates, and run "dracut -f --kver <kernel_version>"
so initramfs for this kernel version is regenerated, for example:

touch /lib/firmware/3.10.0-862.9.1/disallow-intel-06-8f-08
    /usr/libexec/microcode_ctl/update_ucode
    dracut -f --kver 3.10.0-862.9.1

To disable usage of the newer microcode revision for all kernels, please create
file "/etc/microcode_ctl/ucode_with_caveats/disallow-intel-06-8f-08", run
"/usr/libexec/microcode_ctl/update_ucode" to update firmware directories
used for late microcode updates, and run "dracut -f --regenerate-all"
so initramfs images get regenerated, for example:

mkdir -p /etc/microcode_ctl/ucode_with_caveats
    touch /etc/microcode_ctl/ucode_with_caveats/disallow-intel-06-8f-0f
    /usr/libexec/microcode_ctl/update_ucode
    dracut -f --regenerate-all

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

Intel Sapphire Rapids Edge Enhanced CPU models (SPR-EE, family 6, model 143, stepping 8) had reports of system exhibiting latency spikes when revsions 0x2b000603 and newer of the microcode are applied. In order to address this, previous 0x2b0005c0 revision of the microcode is provided, and the usage of the latest microcode can be disabled (see below), so the older version is used instead. For the reference, SHA1 checksums of 06-8f-08 microcode files containing microcode revisions in question are listed below: * 06-8f-08, revision 0x2b0005c0: adf8b6aa2718ff16f3d19d34ec389270073d2b5e * 06-8f-08, revision 0x2b000603: 729014bd05dfb6593152ea7ee12330791bc22bec * 06-8f-08, revision 0x2b000620: e39812f7aff520c79f3f6fa013bd501781d92f8e * 06-8f-08, revision 0x2b000639: 39d91f7a962245ba79fea0611732c86efbd71bc5 Please contact your system vendor for a BIOS/firmware update that contains the latest microcode version. The information regarding disabling microcode update is provided below. To disable usage of the newer microcode revision for a specific kernel version, please create a file "disallow-intel-06-8f-08" inside /lib/firmware/ directory, run "/usr/libexec/microcode_ctl/update_ucode" to update firmware directory used for late microcode updates, and run "dracut -f --kver " so initramfs for this kernel version is regenerated, for example: touch /lib/firmware/3.10.0-862.9.1/disallow-intel-06-8f-08 /usr/libexec/microcode_ctl/update_ucode dracut -f --kver 3.10.0-862.9.1 To disable usage of the newer microcode revision for all kernels, please create file "/etc/microcode_ctl/ucode_with_caveats/disallow-intel-06-8f-08", run "/usr/libexec/microcode_ctl/update_ucode" to update firmware directories used for late microcode updates, and run "dracut -f --regenerate-all" so initramfs images get regenerated, for example: mkdir -p /etc/microcode_ctl/ucode_with_caveats touch /etc/microcode_ctl/ucode_with_caveats/disallow-intel-06-8f-0f /usr/libexec/microcode_ctl/update_ucode dracut -f --regenerate-all Please refer to /usr/share/doc/microcode_ctl/README.caveats for additional information.