Re: [Xen-devel] System Secondary HPETs

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.06.14 at 19:08, <andrew.cooper3@xxxxxxxxxx> wrote:
> Recently, I debugged an issue with a failure to kexec because the kdump
> kernel could not connect up the timer interrupt through the IOAPIC.
> 
> In reality, the problem was not the interrupt routing, but that the
> timer itself was not generating interrupts. , yet advertising it in the
> DSDT as an HPET device.
> 
> The root problem is that the system is not advertising the primary HPET
> in an HPET ACPI table...
> 
> [root@bear ~]# xl dmesg | grep -i hpet
> (XEN) [    2.662941] CPUIDLE: disabled due to no HPET. Force enable with
> 'cpuidle'.
> 
> yet advertising it in the DSDT to dom0:

Not exactly:

> [root@bear ~]# dmesg | grep -i hpet
> [    0.038884] pci 0000:00:1f.0: Force enabled HPET at 0xfed00000

This line indicates that the chipset was recognized without any help
from the ACPI tables - see the various *_force_enable_hpet() in
arch/x86/kernel/quirks.c. This may want to be overridden by Xen
specific initialization code (short of hiding the HPET_TIMER config
option as we do in the legacy kernel).

Jan


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