[Bug 1900149] Re: Microcode update causes hard lockups in Intel N4200 CPU/SoC

[Ascaris]

Not sure how kdeconnect got in there... that was from another big I
filed, not this one.

** Package changed: kdeconnect (Ubuntu) => intel-microcode (Ubuntu)

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https://bugs.launchpad.net/bugs/1900149

Title:
  Microcode update causes hard lockups in Intel N4200 CPU/SoC

Status in intel-microcode package in Ubuntu:
  New

Bug description:
  Months ago, my Acer Swift SF113-31-P5CK laptop (running KDE Neon or
  Kubuntu) began to hard lock at seemingly random intervals, ignoring
  sysrq+REISUB and requiring a force-off. After some trial and error, I
  tried removing the pertinent microcode file (06-5c-09) from
  /lib/firmware/intel-ucode and updating the initramfs, and the lockup
  never happened again. After I discovered that, I checked, and indeed,
  the onset of the lockups coincided with the delivery of the latest
  Intel microcode by Ubuntu.

  I then tried inserting the second newest microcode file into
  /lib/firmware/intel-ucode and updated the initramfs, and again, no
  lockups. They previously happened anywhere from 5 minutes to a few
  hours into a session, and often multiple times a day.

  By now it has been several months since the last lockup, and I use the
  laptop hours each day. I could not get through a day without a lockup
  with the newest microcode file (0x38) in use, and often there were
  multiples per day.

  
  The faulty microcode for the Intel Pentium Silver N4200 SoC that my Swift uses is 0x38, which is the newest, as far as I know, so that's the one the Ubuntu update delivers. The one I am using now is 0x32, the previous one before 0x38, and it's been in use for over a thousand hours with no lockup.

  I saw a recent Microsoft info bulletin describing the newest Windows
  microcode update at the time, and I noticed that the microcode listed
  for my CPU in that update was 0x32. The prior Microsoft microcode
  update showed 0x38, and there was a footnote for the bulletin that
  mentioned it had been reverted (though it didn't say why). I can only
  conclude that I was not the only one having problems with the 0x38
  release of 06-5c-09 (SHA256
  9f6d3bef49d33dfc556aedb94670c6c347662d9c3cb9ececd58e23cd636512fc).

  Not surprisingly, I had the same experience with non-Ubuntu distros
  (OpenSUSE and Fedora). If 0x38 was loaded, it was going to lock up
  frequently.

  I think 0x38 was probably one of the Spectre or Meltdown ucode
  updates, but it's no good if the thing causes PCs to lock up in 5
  minutes of use. Until/unless Intel decides to release a version that
  actually works as intended, I think 0x32 is the lesser of the two
  evils.

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