On: Intel Skylake/Kaby Lake processors: broken hyper-t...

[rwmj]

So if I understand correctly, some affected processors can be fixed by a microcode update, but there are some which cannot be fixed at all?

Also the advisory seems to imply that the OCaml compiler uses gcc for code generation, which it does not -- it generates assembly directly, only using gcc as a front end to the linker.

[brianwawok → rwmj]

Sounds like they can be fixed by the patch isn't out yet?

[tom_mellior → rwmj]

> advisory seems to imply that the OCaml compiler uses gcc for code generation, which it does not -- it generates assembly directly

Yes, but that assembly code contains calls into the OCaml runtime, for garbage collection etc. If I understand correctly, the particular loop affected by this bug was somewhere in this memory management code. That code is written in C and compiled with a C compiler.

[dooglius → rwmj]

It sounds like they can all be fixed by disabling hyperthreading.

[libeclipse → dooglius]

> fixed

mitigated

[a3_nm → dooglius]

Assuming the BIOS/UEFI has an option for it... my laptop doesn't seem to have one (and there are no updates to fix the bug either...).

[bhouston → rwmj]

What is the percentage of non fixable chips for Skylake and kabylake? Sometimes those early steppings are not widely distributed.

[mschuster91 → bhouston]

According to the mail, the systems "cannot be fixed" because they lack HyperThreading in the first place so there is no fix to apply.