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/<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.