Re: [REGRESSION] ACPI processor/cpuidle change in 6.18.52 breaks bare-metal Xen dom0 boot

[Support TRINITY]

Hello,

Thank you, that makes sense and matches the behavior I observed.

The Alpine 6.18.52 kernel fails as Xen dom0, while restoring the previous
ACPI idle registration lifecycle makes it boot again. That is consistent
with 13ebeef6a1b9 being present in 6.18.y without the later dependency
that avoids calling acpi_processor_power_init() in the !cpuidle_get_driver()
case.

I will try testing 6.18.52 with commit 0089ce1c056a ("ACPI: processor:
Update cpuidle driver check in __acpi_processor_start()") applied,
instead of using my lifecycle revert.

If that boots successfully on the affected Alpine Xen dom0 hosts, I will
report the result here.

Thanks,
Tony


-----Message original-----
De: Rafael J. Wysocki (Intel) <rafael@xxxxxxxxxx>
à: Support TRINITY <support@xxxxxxxxxxxxxxx>
Cc: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>; Rafael J. Wysocki (Intel) <rafael@xxxxxxxxxx>; regressions <regressions@xxxxxxxxxxxxxxx>; linux-acpi <linux-acpi@xxxxxxxxxxxxxxx>; linux-pm <linux-pm@xxxxxxxxxxxxxxx>; xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>; linux-kernel <linux-kernel@xxxxxxxxxxxxxxx>; Stable <stable@xxxxxxxxxxxxxxx>
Envoyé: lundi 21 septembre 2026 20:07 CEST
Sujet : Re: [REGRESSION] ACPI processor/cpuidle change in 6.18.52 breaks bare-metal Xen dom0 boot


On Mon, Sep 21, 2026 at 7:46 PM Support TRINITY <support@xxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> Thank you, this matches what I see on the affected Alpine Xen dom0
> systems.
>
> I also tested Linux 6.18.52 with processor=nocst on the Linux kernel
>
> Result: it still fails with the same black screen before dom0 userspace
> and networking come up.
>
> Marek's trace looks consistent with the failure mode I isolated: the
> crash happens from acpi_processor_power_init() while registering the
> cpuidle device.

I think I know what the problem is, see

https://lore.kernel.org/linux-acpi/CAJZ5v0h4giv53a2mPvJYT=fvBTj7vVXs=b7+qC2Q2L35qSTOSA@xxxxxxxxxxxxxx/