New HyperThreading Flaw Affects Intel 6th And 7th Generation Skylake and Kaby Lake-Based Processors (hothardware.com)

MojoKid writes: A new flaw has been discovered that impacts Intel 6th and 7th Generation Skylake and Kaby Lake-based processors that support HyperThreading. The issue affects all OS types and is detailed by Intel errata documentation and points out that under complex micro-architectural conditions, short loops of less than 64 instructions that use AH, BH, CH or DH registers, as well as their corresponding wider register (e.g. RAX, EAX or AX for AH), may cause unpredictable system behavior, including crashes and potential data loss. The OCaml toolchain community first began investigating processors with these malfunctions back in January and found reports stemming back to at least the first half of 2016.

The OCaml team was able pinpoint the issue to Skylake's HyperThreading implementation and notified Intel. While Intel reportedly did not respond directly, it has issued some microcode fixes since then. That's not the end of the story, however, as the microcode fixes need to be implemented into BIOS/UEFI updates as well and it is not clear at this time if all major vendors have included these changes in their latest revisions.

Comments

Apocryphal ....

[brantondaveperson]

.. doesn't mean what the article writer appears to think it means.

Anyhow, that a new highly complex processor contains subtle bug that's fixable without hardware modification isn't exactly earth-shaking news, surely? How about they just fix it, and we move on.

Re:BTW, AMD has a similar bug too

[gweihir]

The difference is that Ryzen is a new architecture, where this is sort-of expected. Intel has this in an old architecture and that is just not acceptable.