-----Original Message-----
From: acrn-users@... <acrn-users@...> On
Behalf Of Tomasz Bursztyka
Sent: Tuesday, April 28, 2020 8:19 PM
To: acrn-users@...
Subject: [acrn-users] HPET and IRQs

Hi,

I am currently trying to fix an issue with Zephyr running as UOS.

The default configuration of Zephyr for acrn enables the LOAPIC timer, but
there does not seem to be any mention of such timer in acrn. Unless I am
missing something.

[Like] LOAPIC is short for local APIC, right? In ACRN, we use LAPIC instead.

When running zephyr with such timer, the timing get all bogus. 60 seconds
looks like 5 seconds, etc... Timings are all off.

[Like] As I know, zephyr won't do runtime timer calibration. You may need to do the calibration manually, and update the code to the correct timer frequency.

As HPET is supported by acrn, I switched the timer to HPET. But now I have a
new issue, acrn-dm displays:

hpet t0 configured invalid irq 2, allowed_irqs 0xff000000

And nothing proceeds, since acrn defaults to 0, zephyr isr for hpet is never
called.

Indeed Zephyr sets HPET IRQ to 2, which seems to be wrong then for acrn .

Which IRQ should HPET timer be configured to use on UOS side then?

[Like] HPET may use IRQ 24~31. As well, HPET calibration is needed, so we recommend you to use the LAPIC timer.

Thanks,

Tomasz