Re: HPET and IRQs

Geoffroy Van Cutsem

-----Original Message-----
From: acrn-users@... <acrn-users@...>
On Behalf Of Yan, Like
Sent: Wednesday, April 29, 2020 5:24 PM
To: acrn-users@...
Subject: Re: [acrn-users] HPET and IRQs

Hi Tomasz,

If you launched VM with --lapic_pt, then it's a RT VM.
An RT VM is only allowed to be powered-off/reset when initiated inside the
RT VM. The design principle here is that the other VMs (even the SOS VM)
should not interfere RT VM to guarantee the RT performance.
And there are some limitations as to RT VM, legacy devices are not
supported, such as vHPET.
Here are 2 documents for RT VM:
Thanks for the information Like. I was suspecting this but couldn't find a good reference about this in our documentation. The couple of documents you referenced above provide some good background information and useful tips on how to run RTVMs on ACRN. It does not really talk about what this limitation for example. It would be great to have some High-Level Design Guide that talk more extensively about the different types of User VMs: i.e. pre-launched, post-launched and RTVM vs. "normal" User VMs.

Is this something we can plan to add?



-----Original Message-----
From: acrn-users@...
<acrn-users@...> On Behalf Of Tomasz Bursztyka
Sent: Wednesday, April 29, 2020 2:37 PM
To: acrn-users@...
Subject: Re: [acrn-users] HPET and IRQs

Hi Like,

VM or RT VM, I don't know. It did not occur to me there was an actual
difference, I just used the launcher script for zephyr. I'll check.

I could get LAPIC (which we indeed call LOAPIC) to work using --
lapic_pt option to acrn-dm. But then I am unable to stop/reset/delete
the VM for some reason (even with --force on stop, it always returns -1).

I'll still investigate about HPET. It "should" work, and if Zephyr is
missing some support - runtime calibration that is - then it will be worth
adding it.

Thanks for the inputs,


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