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[Bug 1084373] Re: [Feature] Early load microcode for x86 CPU


I've reproduced the problem. Somehow 'CONFIG_MICROCODE_INTEL_EARLY is
not set' in Utopic, whereas it _is_ enabled in Trusty.

** Package changed: initramfs-tools (Ubuntu) => linux (Ubuntu)

** Changed in: linux (Ubuntu)
       Status: New => In Progress

** Changed in: linux (Ubuntu)
     Assignee: (unassigned) => Tim Gardner (timg-tpi)

** Information type changed from Private to Public

** Also affects: linux (Ubuntu Utopic)
   Importance: Undecided
     Assignee: Tim Gardner (timg-tpi)
       Status: In Progress

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  [Feature] Early load microcode for x86 CPU

Status in intel:
Status in “linux” package in Ubuntu:
  In Progress
Status in “linux” source package in Utopic:
  In Progress

Bug description:
  The problem in current microcode loading method is that we load a
  microcode way too late; ideally we should load it before turning
  paging on.  This may only be practical on 32 bits since we can't get
  to 64-bit mode without paging on,but we should still do it as early as
  at all possible.

  Similarly, we should load the microcode update as early as possible
  during AP bringup and when processors are brought back online after
  hotplug or S3/S4.

  In order to do that, the microcode patch needs to be permanently
  present in kernel memory.  Each individual patch is fairly small, so
  that is OK, but the entire blob with support for each CPU is too big.
  Since only CPU's with same model can be in the same platform, we store
  microcode with the same model as BSP. Later on AP's can upload
  microcode from the saved microcodep patches.

  Note, however, that Linux users have gotten used to being able to
  install a microcode patch in the field without having a reboot; we
  support that model too.

  Upstream schedule:

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