linux-generic-hwe-24.04 version 6.11.0-19.19~24.04.1 fail to properly detect CPU core and thread count with 'noapic'

[SunBear]

After doing `sudo apt upgrade`, the above mentioned linux hwe kernel was installed.

Start-Date: 2025-03-05 15:02:08
Commandline: apt upgrade
Requested-By: user (1000)
Install: linux-objects-nvidia-470-6.11.0-19-generic:amd64 (6.11.0-19.19~24.04.1, automatic), linux-hwe-6.11-tools-6.11.0-19:amd64 (6.11.0-19.19~24.04.1, automatic), linux-modules-extra-6.11.0-19-generic:amd64 (6.11.0-19.19~24.04.1, automatic), linux-modules-nvidia-470-6.11.0-19-generic:amd64 (6.11.0-19.19~24.04.1, automatic), linux-image-6.11.0-19-generic:amd64 (6.11.0-19.19~24.04.1, automatic), linux-tools-6.11.0-19-generic:amd64 (6.11.0-19.19~24.04.1, automatic), linux-signatures-nvidia-6.11.0-19-generic:amd64 (6.11.0-19.19~24.04.1, automatic), linux-hwe-6.11-headers-6.11.0-19:amd64 (6.11.0-19.19~24.04.1, automatic), linux-headers-6.11.0-19-generic:amd64 (6.11.0-19.19~24.04.1, automatic), linux-modules-6.11.0-19-generic:amd64 (6.11.0-19.19~24.04.1, automatic)
Upgrade: linux-headers-generic-hwe-24.04:amd64 (6.8.0-52.53, 6.11.0-19.19~24.04.1), linux-generic-hwe-24.04:amd64 (6.8.0-52.53, 6.11.0-19.19~24.04.1), linux-tools-common:amd64 (6.8.0-54.56, 6.8.0-55.57), google-chrome-stable:amd64 (133.0.6943.141-1, 134.0.6998.35-1), linux-modules-nvidia-470-generic-hwe-24.04:amd64 (6.8.0-52.53, 6.11.0-19.19~24.04.1), linux-image-generic-hwe-24.04:amd64 (6.8.0-52.53, 6.11.0-19.19~24.04.1), linux-libc-dev:amd64 (6.8.0-54.56, 6.8.0-55.57)
End-Date: 2025-03-05 15:03:19

After rebooting, the new linux kernel fails to correctly detect the CPU core and thread count. This system CPU has 16 cores, 32 threads and System Monitor normally shows 32 CPU virtual cores. After the upgrade, System Monitor now shows only 1 CPU virtual core. The upgrade corrupted my system.

To circumvent this issue, I have to boot Ubuntu 24.04 using the linux-image-6.8.0-52-generic 6.8.0-52.53 kernel and not use the hwe kernel.

I have submitted the relevant `ubuntu-bug` report.

How do I fix this issue?

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: ubuntu-release-upgrader-core 1:24.04.22 [origin: unknown]
ProcVersionSignature: Ubuntu 6.11.0-19.19~24.04.1-generic 6.11.11
Uname: Linux 6.11.0-19-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.28.1-0ubuntu3.1
Architecture: amd64
CasperMD5CheckResult: pass
CrashDB: ubuntu
CrashReports: 640:1000:109:51661892:2025-03-03 02:30:21.363597393 +0800:2025-03-04 00:28:42.503056252 +0800:/var/crash/_opt_brave.com_brave_brave.1000.crash
CurrentDesktop: ubuntu:GNOME
Date: Thu Mar 6 12:16:18 2025
InstallationDate: Installed on 2024-12-07 (89 days ago)
InstallationMedia: Ubuntu 24.04.1 LTS "Noble Numbat" - Release amd64 (20240827.1)
PackageArchitecture: all
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 XDG_RUNTIME_DIR=<set>
SourcePackage: ubuntu-release-upgrader
Symptom: release-upgrade
UpgradeStatus: No upgrade log present (probably fresh install)

[SunBear (sunbear-c22)]

Another point worth noting. The issue that I have reported does not occur when I boot in via Linux 6.11.0-19-generic (recovery mode) but occurs for Linux 6.11.0-19-generic.

[Chris Guiver (guiverc)]

Thank you for taking the time to report this bug and helping to make Ubuntu better.

Bug reporting is about finding & fixing problems thus preventing future users from hitting the same bug.

I suspect a Support site would be more appropriate, eg. https://answers.launchpad.net/ubuntu. You can also find help with your problem in the support forum of your local Ubuntu community http://loco.ubuntu.com/ or asking at https://askubuntu.com or https://discourse.ubuntu.com/t/welcome-to-support-and-help/49951, or for more support options please look at https://discourse.ubuntu.com/t/community-support/709

FYI: The ubuntu-release-upgrader tool you've filed against will release-upgrade a system to a newer release, ie. make a 24.04 system 24.10 after reboot. Your install was 24.04 and you've not yet release-upgraded to a later release (ie. you're not using 24.10); thus haven't used that tool.

By filing about an incorrect (and not used) tool, kernel details were not obtained as the release-upgrade process works on updating packages, so more detail maybe required before this report can be worked on (limited kernel details were auto-added)

[Daniel Letzeisen (dtl131)]

Probably caused by you booting with 'noapic' (fixed in kernel 6.13.x):
https://github.com/torvalds/linux/commit/73da582a476ea6e3512f89f8ed57dfed945829a2

A Fedora user found things worked when they switched noapic to pci=nobar

[Daniel Letzeisen (dtl131)]

Also, note there is an updated BIOS for your system with "Enhance system stability and compatibility"
Maybe it fixes whatever causes you to boot with noapic and acpi=force. Maybe not..

https://www.asus.com/us/motherboards-components/motherboards/prime/prime-x299-a-ii/helpdesk_bios?model2Name=Prime-X299-A-II

[Tim Whisonant (tswhison)]

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 2100999

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that and change the bug status to 'Confirmed'.

[Juerg Haefliger (juergh)]

'apport-collect 2100999' will not collect additional data due to bug #2018128.

[SunBear (sunbear-c22)]

@ChrisGuiver(guiverc)

Before raising this bug report, I hard raised my issue in AskUbuntu (https://askubuntu.com/q/1542959/541417). I was advised to raise a bug report from there. My apologies for filing this bug against release-upgrade. To be honest, despite the simplicity of the `ubuntu-bug` GUI, the difficulty I faced was really not knowing which category to file the bug report under.

@DanielLetzeisen

Thanks for informing about the latest firmware for my motherboard. I have update it. However that firmware update did not resolve my issue. Instead, I managed to resolve my issue by replacing the "noapic acpi=force" in /etc/default/grub with "intel_iommu=on iommu=pt", followed by sudo update-grub; sudo reboot. So, the number of virtual CPU cores are correctly shown on System Monitor.