Re: Cpufreq drivers not working on T480S

[Milky <milky_way_303030@xxxxxxxxx>]

On Tuesday, January 6th, 2026 at 1:06 AM, Jason Andryuk <jandryuk@xxxxxxxxx> 
wrote:

> > As suggested, I added the debug parameters to the dom0 kernel. Before or
> > after `modprobe xen-acpi-processor dyndbg==pmf`, there is no useful
> > debug information that I could find, apart from the
> > `xen_acpi_processor:get_max_acpi_id` message as seen below.
> > 
> > ```
> > # sudo dmesg | grep xen.acpi
> > [ 2.282851] Kernel command line: placeholder 
> > root=/dev/mapper/qubes_dom0-root ro rd.luks.uuid=<...> 
> > rd.lvm.lv=qubes_dom0/root rd.lvm.lv=qubes_dom0/swap 
> > plymouth.ignore-serial-consoles 6.6.77-1.qubes.fc37.x86_64 x86_64 rhgb 
> > loglevel=9 "dyndbg=module xen_acpi_processor +p" 
> > "xen_acpi_processor.dyndbg=func * +p" rd.qubes.hide_all_usb
> > [ 5.224092] xen_acpi_processor: Max ACPI ID: 6
> 
> 
> You successfully turned on dyndbg to get that output, but there is no
> further output. This makes me think something else is wrong and
> xen-acpi-processor doesn't upload anything.
> 
> The call here 
> https://elixir.bootlin.com/linux/v6.18.2/source/drivers/xen/xen-acpi-processor.c#L557
> to
> https://elixir.bootlin.com/linux/v6.18.2/source/drivers/acpi/processor_perflib.c#L421
> goes into some acpi code. Maybe there are other messages in dmesg
> around the same time? Maybe you'd have to turn on more debugging to
> get them.

I'm dumping below a few more entries from the same dmesg log. 

```
[    5.175506] xen:xen_evtchn: Event-channel device installed
[    5.208487] xen_pciback: backend is vpci
[    5.215060] xen_acpi_processor: Max ACPI ID: 6
[    5.721955] pciback 0000:00:14.0: xen_pciback: seizing device
[    5.722265] xen: registering gsi 16 triggering 0 polarity 1
[    5.722288] Already setup the GSI :16
[    5.723125] pciback 0000:00:1f.6: xen_pciback: seizing device
[    5.723389] xen: registering gsi 16 triggering 0 polarity 1
[    5.723408] Already setup the GSI :16
[    5.829865] pciback 0000:02:00.0: xen_pciback: seizing device
[    5.832192] xen: registering gsi 18 triggering 0 polarity 1
[    5.832214] Already setup the GSI :18
[    7.476065] nvme nvme0: pci function 0000:03:00.0
[    7.476438] xen: registering gsi 16 triggering 0 polarity 1
[    7.476459] Already setup the GSI :16
[    7.486102] nvme nvme0: 4/0/0 default/read/poll queues
[    7.489856]  nvme0n1: p1 p2
[    8.877791] xen: registering gsi 16 triggering 0 polarity 1
[    8.877823] Already setup the GSI :16
[    8.877910] i915 0000:00:02.0: [drm] Found KABYLAKE (device ID 5917) display 
version 9.00 stepping C0
```

> You could de-compile the ACPI tables and see if they have CPU info.
> Something like:
> mkdir acpi-tables
> cd acpi-tables
> cp /sys/firmware/acpi/tables/* .
> iasl -d *
> grep -r -e _PCT -e _PPC -e _PSS *.dsl
> 
> That could help confirm the tables are missing.

Unfortunately it would appear so. Grepping doesn't return any results. 

The same is also true under Debian Live; does it mean that frequency scaling, 
since it seems to be working under Debian Live, doesn't always rely on this?

I'm currently trying to find someone else with a librebooted T480S to check 
their ACPI tables, since I'm wondering if I botched my libreboot build.