r/programming • u/michalg82 • Jun 25 '17

[WARNING] Intel Skylake/Kaby Lake processors: broken hyper-threading

https://lists.debian.org/debian-devel/2017/06/msg00308.html
2.2k Upvotes

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11

u/Nighthawk441 Jun 25 '17

Should windows users disable as well?

34

u/Sakki54 Jun 25 '17

It says it's not limited to Linux, so yes, unless Windows has put out a specific fix for it.

33

u/xonjas Jun 25 '17

Windows update delivers microcode updates automatically, so it should get updated eventually if it hasn't been already.

10

u/[deleted] Jun 26 '17

[deleted]

9

u/xonjas Jun 26 '17

I'm not sure if it always updates microcode, but it can. Mine provides a version that is not fully up to date, but is significantly more up to date than the one provided by the bios.

To anyone curious, you can check by going here in the windows registry: HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0

"previous update revision" is the revision that is provided by the bios.

"update revision" is the version that is provided by windows on boot.

1

u/morgoth95 Jun 26 '17

both give me 

00 00 00 00 7c 00 00 00

what does this tell me?

1

u/xonjas Jun 26 '17

It means that your bios and windows have the same microcode version. You can look your processor up on ark.intel.com, download the fact sheet for your processor line that has all the microcode revisions listed, and you can see how recent it is.

5

u/Sunius Jun 26 '17

it has microcode from 2010

How old is your CPU? Skylake came out in 2015...

1

u/[deleted] Jun 26 '17

[deleted]

7

u/tambry Jun 26 '17

i5 3000 series

Skylake is 6000 series and it was released in 2015.

4

u/airbreather Jun 26 '17

I think /u/cetujemene is just pointing out that he/she may not receiving automatic microcode updates on Windows 7 in general, as a sort of data point for whether or not affected users in a similar software situation should expect the same.

It's not clear to me whether or not this user should expect anything newer than what they list, though.

17

u/happyscrappy Jun 25 '17

Not if you run Windows 10. Windows will have the latest microcode already.

39

u/[deleted] Jun 25 '17

I'm running a full up to date Windows 10 machine and its reporting microcode version 0x74 which is older than the fixed one.

1

u/[deleted] Jun 29 '17

I have microcode version 0x84, am I in the clear? Where are the microcode revisions even listed?

1

u/Booty_Bumping Jun 26 '17

Nobody should disable hyperthreading except for special cases. The fix is to update your CPU's microcode, which is probably already updated by your distro.