Created attachment 875310 [details]
excerpt of the journal on kernel 6.9.1

(based on forum thread:
https://forums.opensuse.org/t/since-kernel-6-9-running-on-only-1-core/175460)

Since updating my openSUSE Tumbleweed install from kernel 6.8.9 to kernels
6.9.x, all my applications (such as firefox) run on mostly only 1 core of the
CPU.

CPU is AMD FX 8350 8 core (as 4 modules of 2 half-cores which share their FPU)
Motherboard is GA-990FXA-UD7 (rev 1.x) (firmware is BIOS with some EFI
compatibility layer. Not UEFI like rev 3.x)

on kernels 6.9.1 and 6.9.3, while smpboot is initialising the other cores, I
get a bunch of errors, which disappear if I boot into version 6.8.9 instead
(See linked thread / attachment).

This is then followed by:
> boot.6.9.txt:jun 03 10:02:33 saturn kernel: mtrr: your CPUs had inconsistent variable MTRR settings
> boot.6.9.txt:jun 03 10:02:33 saturn kernel: mtrr: probably your BIOS does not setup all CPUs.
> boot.6.9.txt:jun 03 10:02:33 saturn kernel: mtrr: corrected configuration.

What would be the next best step to gather information useful to understand
bug?