https://newsroom.intel.com/wp-content/uploads/sites/11/2018/04/microcode-update-guidance.pdf
From https://www.theregister.co.uk/2018/04/04/intel_spectre_microcode_updates/ "The new guidance <https://newsroom.intel.com/wp-content/uploads/sites/11/2018/04/microcode-update-guidance.pdf>, issued April 2, adds a “stopped” status to Intel’s “production status” category in its array of available Meltdown and Spectre <https://www.theregister.co.uk/2018/01/04/intel_amd_arm_cpu_vulnerability/> security updates. "Stopped" indicates there will be no microcode patch to kill off Meltdown and Spectre." " "Stopped" CPUs that won’t therefore get a fix are in the Bloomfield, Bloomfield Xeon, Clarksfield, Gulftown, Harpertown Xeon C0 and E0, Jasper Forest, Penryn/QC, SoFIA 3GR, Wolfdale, Wolfdale Xeon, Yorkfield, and Yorkfield Xeon families. The new list includes various Xeons, Core CPUs, Pentiums, Celerons, and Atoms – just about everything Intel makes. Most the CPUs listed above are oldies that went on sale between 2007 and 2011"