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Intel's Skylake and Kaby Lake CPUs Have Nasty Microcode Bug

posted by takyon on Monday June 26 2017, @09:35PM   
from the skylake-axed dept.

"exec" writes:

Arthur T Knackerbracket has found the following story:

During April and May, Intel started updating processor documentation with a new errata note, and over the weekend we learned why: Skylake and Kaby Lake silicon has a microcode bug.

The errata is described in detail on the Debian mailing list, and affects Skylake and Kaby Lake Intel Core processors (in desktop, high-end desktop, embedded and mobile platforms), Xeon v5 and v6 server processors, and some Pentium models.

The Debian advisory says affected users need to disable hyper-threading "immediately" in their BIOS or UEFI settings, because the processors can "dangerously misbehave when hyper-threading is enabled."

Symptoms can include "application and system misbehaviour, data corruption, and data loss".

Henrique de Moraes Holschuh, who authored the Debian post, notes that all operating systems, not only Linux, are subject to the bug.

Also at Tom's Hardware and Ars Technica.

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Original Submission

• Re:How to tellRe:How to tell (Score: 3, Informative) by jasassin on Monday June 26 2017, @10:16PM (1 child)

  by jasassin (3566) <jasassin@gmail.com> on Monday June 26 2017, @10:16PM (#531599) Homepage Journal

  Here's a nice perl script some kind soul wrote you can run on your Ubuntu system to see if it is affected:

  https://lists.debian.org/debian-devel/2017/06/msg00309.html [debian.org]

  --
  jasassin@gmail.com GPG Key ID: 0xE6462C68A9A3DB5A

  Parent

  Starting Score:	1		point
  Moderation		+1
  Informative=1, Total=1
  Extra 'Informative' Modifier		0
  Karma-Bonus Modifier		+1
  Total Score:		3

• Re:How to tell(Score: 4, Informative) by kaszz on Monday June 26 2017, @10:31PM

  by kaszz (4211) on Monday June 26 2017, @10:31PM (#531604) Journal

  This seems to be the essence of it (and can be decoded manually using dmesg):

  if( $vendor eq "GenuineIntel" and $family == 6) {
                          if ($model == 78 or $model == 94) {
                                  if ($stepping eq "3") {
                                          print "Your CPU is affected, ";
                                          if (hex($microcoderev) >= 0xb9) {
                                                  print "but your microcode is new enough\n";
                                          } elsif ($hyperthreading ne "on") {
                                                  print "but hyper threading is off, which works around the problem\n";
                                          } else {
                                                  print "you should install the latest intel-microcode\n";
                                          }

  Parent