On 9/3/21 11:41 PM, Marek Marczykowski-Górecki wrote:
[...]I'm confused. I was under the impression that Qubes OS (after the QSB-043
patches) automatically disables hyper-threading for you such that you don't
have to know anything, do anything, or read any past QSBs.
[....]
There are (at least) two ways to disable hyper-threading:
1. In system BIOS (if there is such option)
2. In software - by disabling every second thread of each core.
The QSB-043 uses the second method. It has is drawbacks, as the logic to
bring up and down CPUs is quite complex. And yes, there are known
issues[1] affecting suspend. Disabling hyper-threading in BIOS, prevents
Xen from starting those secondary threads at all, and so it doesn't need
to bring them down.
[....]
This is kind of similar issue as the one discussed here. That's why it's
better to disable HT in BIOS - to not show those 8 CPUs at all. But from
the OS level, we don't have other choice, and we prefer a secure
default - that's why we disable HT at Xen level, to provide safer option
regardless of what user has set in the BIOS.
Couldn't xen/qubes set a boot warning to users that rely only on (2) to
encourage more strongly to disable by BIOS (1)? That seems a logic
measure to me. best, Bernhard
--
You received this message because you are subscribed to the Google Groups
"qubes-users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to qubes-users+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/qubes-users/c52d5e57-a3d3-fc55-ee67-d2032095fdd5%40web.de.
