Announcement

**die.boer** · Sep 05, 2026, 12:31 PM

It sounds like a shutdown/reboot process hanging near the very end, rather than a problem with GRUB or the normal boot process.
can you try

Code:

sudo reboot

and see if it still hangs ?
if it does and you have to press the button on PC to restart , then right after PC starts ,run

Code:

journalctl -b -1 -e

and post the last 30-50 lines here

**Qqmike** · Sep 05, 2026, 12:49 PM

It DID hang, btw, and I pressed the PC's restart button.

journalctl -b -1 -e
Sep 05 12:31:15 mike-System-Product-Name anacron[14759]: Anacron 2.3 started on 2026-09-05
Sep 05 12:31:15 mike-System-Product-Name anacron[14759]: Normal exit (0 jobs run)
Sep 05 12:32:10 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:32:10 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:33:34 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:33:34 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:34:11 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:34:11 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:35:03 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:35:03 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:36:12 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:36:12 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:36:20 mike-System-Product-Name cups.cups-browsed[1456]: + true
Sep 05 12:36:20 mike-System-Product-Name cups.cups-browsed[1456]: + sleep 3600
Sep 05 12:37:40 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:37:40 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:38:12 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:38:12 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:39:13 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:39:13 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:42:13 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:42:13 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:44:05 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:44:05 mike-System-Product-Name rtkit-daemon[1487]: Supervising 7 threads of 4 processes of 1 users.
Sep 05 12:45:29 mike-System-Product-Name systemd[1598]: Started Konsole - Terminal.
Sep 05 12:45:43 mike-System-Product-Name sudo[15278]: pam_unix(sudo:auth): authentication failure; logname=mike uid=1000 euid=0 tty>
Sep 05 12:45:54 mike-System-Product-Name sudo[15278]: mike : TTY=pts/1 ; PWD=/home/mike ; USER=root ; COMMAND=/usr/sbin/reboot
Sep 05 12:45:54 mike-System-Product-Name sudo[15278]: pam_unix(sudo:session): session opened for user root(uid=0) by mike(uid=1000)
lines 1063-1090/1090 (END)

Note: "authentication failure": that was me -- I typed my PW wrong, tried again and got it right

**die.boer** · Sep 05, 2026, 12:51 PM

nothing looks suspicious there
can you post output of

Code:

journalctl -b -1 -k -p warning

**Qqmike** · Sep 05, 2026, 01:10 PM

journalctl -b -1 -k -p warning
Sep 05 09:36:18 mike-System-Product-Name kernel: x86/cpu: VMX (outside TXT) disabled by BIOS
Sep 05 09:36:18 mike-System-Product-Name kernel: x86/cpu: SGX disabled by BIOS.
Sep 05 09:36:18 mike-System-Product-Name kernel: MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.ke>
Sep 05 09:36:18 mike-System-Product-Name kernel: #7 #8 #9 #10 #11
Sep 05 09:36:18 mike-System-Product-Name kernel: ENERGY_PERF_BIAS: Set to 'normal', was 'performance'
Sep 05 09:36:18 mike-System-Product-Name kernel: device-mapper: core: CONFIG_IMA_DISABLE_HTABLE is disabled. Duplicate IMA measurem>
Sep 05 09:36:18 mike-System-Product-Name kernel: ata1.00: supports DRM functions and may not be fully accessible
Sep 05 09:36:18 mike-System-Product-Name kernel: ata1.00: supports DRM functions and may not be fully accessible
Sep 05 09:36:18 mike-System-Product-Name systemd[1]: Configuration file /run/systemd/system/netplan-ovs-cleanup.service is marked w>
Sep 05 09:36:18 mike-System-Product-Name systemd[1]: /lib/systemd/system/snapd.service:23: Unknown key name 'RestartMode' in sectio>
Sep 05 09:36:18 mike-System-Product-Name kernel: snd_hda_codec_hdmi hdaudioC0D2: Monitor plugged-in, Failed to power up codec ret=[>
Sep 05 09:36:19 mike-System-Product-Name kernel: kauditd_printk_skb: 36 callbacks suppressed
Sep 05 09:36:38 mike-System-Product-Name kernel: kauditd_printk_skb: 30 callbacks suppressed
Sep 05 09:36:49 mike-System-Product-Name kernel: kauditd_printk_skb: 12 callbacks suppressed
Sep 05 09:36:51 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:36:53 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:36:56 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:36:58 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:01 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:03 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:06 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:08 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:11 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:13 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:16 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:18 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:21 mike-System-Product-Name kernel: usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'ipp-usb' sets config #1
Sep 05 09:37:23 mike-System-Product-Name kernel: usb 1-1.

**die.boer** · Sep 05, 2026, 01:14 PM

ok , and this 1 please ...

Code:

journalctl -b -1 --since "12:45:50" --until "12:46:30"

**Qqmike** · Sep 05, 2026, 01:23 PM

journalctl -b -1 --since "12:45:50" --until "12:46:30"
Sep 05 12:45:54 mike-System-Product-Name sudo[15278]: mike : TTY=pts/1 ; PWD=/home/mike ; USER=root ; COMMAND=/usr/sbin/reboot
Sep 05 12:45:54 mike-System-Product-Name sudo[15278]: pam_unix(sudo:session): session opened for user root(uid=0) by mike(uid=1000)

**Qqmike** · Sep 05, 2026, 02:10 PM

Hmmm ... last two restarts: No problem! I.e., it restarted normally.

**die.boer** · Sep 06, 2026, 12:20 PM

Originally posted by Qqmike View Post

Hmmm ... last two restarts: No problem! I.e., it restarted normally.

is it still restarting properly ?

**Qqmike** · Sep 06, 2026, 01:34 PM

Yes, it is still starting normally. I just tried it about 8 minutes after you posted # 9. Smooth and quick, no visible glitches.

The only thing I have done recently is to change ISP, I dropped CenturyLink and picked up T-Mobile 5G.
The PC remained on WITHOUT any internet for about 24 days, and it was ON while I hooked up the T-Mobile (using Ethernet cable).
Then I used Cups to configure an HP printer, which didn't go smoothly.

No power failures or anything weird like that.

Thanks.

**Qqmike** · Sep 08, 2026, 09:41 AM

Sorry. I may have panicked unnecessarily. Some initial research on these messages suggests that -- quite probably -- I shouldn't have to worry about these warnings. They may be informational for some users.
Is that your take on it?

BUT ... I MAY still have that restart/shutdown issue ... ? a bit of a mystery.

Update:
That SSD I was on above (using K 22.04) has failed following a power outage at the house (and restart)--Long story -- bad unfixable superblocks and bad SSD.
I removed that SSD totally.

Now I am on an M.2. that was already installed in the PC box, and using K 24.04.
I just did a shutdown. It froze. I did a hard restart, then a shutdown, and it shutdown OK.

I'm back in now and ran:
journalctl -b -1 -k -p warning

I got this:

A LOT of lines identical to this:
Sep 08 09:21:50 mike-systemproductname kernel: x86/cpu: VMX (outside TXT) disabled by BIOS
Sep 08 09:21:50 mike-systemproductname kernel: x86/cpu: SGX disabled by BIOS.

A LOT of these lines:
Sep 08 09:21:50 mike-systemproductname kernel: Transient Scheduler Attacks: MMIO Stale Data CPU bug present and SMT on, data leak possible. SSep 08 09:21:50 mike-systemproductname kernel: x86/cpu: VMX (outside TXT) disabled by BIOS
Sep 08 09:21:50 mike-systemproductname kernel: x86/cpu: SGX disabled by BIOS.
Sep 08 09:21:50 mike-systemproductname kernel: Transient Scheduler Attacks: MMIO Stale Data CPU bug present and SMT on, data leak possible. SSepSep 0Sep 08 SepSepSep SepSepSepSep SepSepSepSepSepSepSepSep 0SepSepSeSSeSSeSSepSSSeSSSSSSeSeSeSSepSep 08 09:21:50 mike-systemproductname kernel: x86/cpu: VMX (outside TXT) disabled by BIOS

More of these:
Sep 08 09:21:50 mike-systemproductname kernel: x86/cpu: VMX (outside TXT) disabled by BIOS
Sep 08 09:21:50 mike-systemproductname kernel: x86/cpu: SGX disabled by BIOS.

Ending with this:
Sep 08 09:21:50 mike-systemproductname kernel: Transient Scheduler Attacks: MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.ht>
Sep 08 09:21:50 mike-systemproductname kernel: device-mapper: core: CONFIG_IMA_DISABLE_HTABLE is disabled. Duplicate IMA measurements will not be recorded in the IMA log.
Sep 08 09:21:50 mike-systemproductname kernel: ENERGY_PERF_BIAS: Set to 'normal', was 'performance'
Sep 08 09:21:50 mike-systemproductname kernel: r8169 0000:03:00.0: can't disable ASPM; OS doesn't have ASPM control
Sep 08 09:21:51 mike-systemproductname kernel: mtd: partition "BIOS" extends beyond the end of device "0000:00:1f.5" -- size truncated to 0x800000
Sep 08 09:21:52 mike-systemproductname kernel: kauditd_printk_skb: 174 callbacks suppressed
Sep 08 09:21:52 mike-systemproductname kernel: block nvme0n1: No UUID available providing old NGUID

So, there's where I'm at.
The PC with K 24.04 seems to run fine, but with all that going on ...

**Snowhog** · Sep 08, 2026, 12:12 PM

AI Overview

The kernel warning “MMIO Stale Data CPU bug present and SMT on, data leak possible” means your Intel processor is potentially vulnerable to hardware data sampling flaws via Memory-Mapped I/O, and Simultaneous Multi-Threading (Hyper-Threading) is enabled. [1, 2]

Understanding the Risk

What it means: Stale data left in internal CPU buffers from MMIO operations might be read via speculative execution side-channels across active SMT threads. [1, 2]

Real-world impact: For a standard single-user desktop or personal workstation running Kubuntu 22.04, the actual risk is extremely low because exploitation typically requires local execution capabilities or targeted multi-tenant virtualization access. [1, 2]

How to Check Status

You can check your current kernel vulnerability status in your terminal:

cat /sys/devices/system/cpu/vulnerabilities/mmio_stale_data

Use code with caution.

Mitigation Options

The Linux kernel handles basic mitigations by default via microcode updates, but you can adjust the strictness using boot parameters in /etc/default/grub: [1, 2]

Default / Standard Mitigation: The kernel clears CPU buffers on critical transitions without disabling SMT (balancing security and performance). [1]

Maximum Security (Disable SMT): If you handle highly sensitive data or multi-tenant workloads, you can append mmio_stale_data=full,nosmt to GRUB_CMDLINE_LINUX_DEFAULT, then update GRUB via:

sudo update-grub

Use code with caution.

(Note: Disabling SMT/Hyper-Threading cuts concurrent logical threads in half and may impact CPU performance.) [1, 2, 3, 4]

**Qqmike** · Sep 08, 2026, 06:12 PM

Re: the "restart" issue: No problem with a restart 5 minutes ago.

Re: the warning in Konsole output: The real-world impact on me is minimal. Disabling multi/hyper-threading is not an option for me.
I'm not so much worried about this.
Thanks, Paul.

**die.boer** · Sep 09, 2026, 11:40 PM

does it restart normally now with the M2 ?
x86/cpu: VMX/SGX disabled by BIOS and MMIO Stale Data CPU bug present and SMT on, data leak possible are just standard boot-time kernel messages that appear on basically every Intel machine — they're security advisories about speculative-execution side channels, not error conditions

**Qqmike** · Sep 10, 2026, 07:26 AM

@die.boer

Restart: I just did a K > Restart 5 minutes ago, and it went smoothly and fairly quick.

Weird messages: Thanks for confirming that the ominous-sounding messages are mainly informational.

Announcement

Restart in Kubuntu won't work

Restart in Kubuntu won't work

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