Blame SOURCES/06-8c-01_readme

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Some Intel Tiger Lake-UP3/UP4 CPU models (TGL, family 6, model 140, stepping 1)
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have reports of system hangs when a microcode update, that is included
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since microcode-20201110 update, is applied[1].  In order to address this,
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microcode update has been disabled by default on these systems.
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[1] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/44
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Please contact your system vendor for a BIOS/firmware update that contains
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the latest microcode version.
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The information regarding enforcing microcode update is provided below.
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To enforce usage of the latest 06-8c-01 microcode revision for a specific kernel
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version, please create a file "force-intel-06-8c-01" inside
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/lib/firmware/<kernel_version> directory, run
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"/usr/libexec/microcode_ctl/update_ucode" to add it to firmware directory
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where microcode will be available for late microcode update, and run
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"dracut -f --kver <kernel_version>", so initramfs for this kernel version
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is regenerated and the microcode can be loaded early, for example:
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    touch /lib/firmware/3.10.0-862.9.1/force-intel-06-8c-01
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    /usr/libexec/microcode_ctl/update_ucode
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    dracut -f --kver 3.10.0-862.9.1
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After that, it is possible to perform a late microcode update by executing
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"/usr/libexec/microcode_ctl/reload_microcode" or by writing value "1" to
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"/sys/devices/system/cpu/microcode/reload" directly.
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To enforce addition of this microcode for all kernels, please create file
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"/etc/microcode_ctl/ucode_with_caveats/force-intel-06-8c-01", run
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"/usr/libexec/microcode_ctl/update_ucode" for enabling late microcode updates,
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and "dracut -f --regenerate-all" for enabling early microcode updates:
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    mkdir -p /etc/microcode_ctl/ucode_with_caveats
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    touch /etc/microcode_ctl/ucode_with_caveats/force-intel-06-8c-01
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    /usr/libexec/microcode_ctl/update_ucode
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    dracut -f --regenerate-all
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Please refer to /usr/share/doc/microcode_ctl/README.caveats for additional
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information.