[fedora-virt] How do you disable hpet in a kvm?

[Laine Stump]

On 06/08/2010 02:15 PM, Frederick N. Brier wrote:
> I installed PBX In A Flash (PIAF) as a VM on a Fedora 11 64 bit host.  
> PIAF is a 32 bit CentOS 5.2 distro for running Asterisk.  I, like many 
> others, am getting the error message "rtc: lost some interrupts at 
> 1024hz" repeating over and over on the console.  Some people have 
> apparently gotten rid of this error message by disabling hpet in the 
> BIOS.  However, this is a VM (kvm).
>
> I tried adding nohpet as a kernel parameter in /boot/grub/menu.lst, 
> but that effects the linux OS, not the BIOS.  It did not fix it.
>
> I found references to a -no-hpet qemu parameter.  However, I cannot 
> find how to set it in a VM created using virt-manager and an ISO 
> image.  In the /etc/libvirt of the host I found XML configuration 
> files describing the VMs.  These appear to be the same as those 
> created using the virsh dumpxml command.  There does not appear to be 
> an XML element as there is for acpi and apic.  The man page describing 
> the XML format does not have an HPET related option.  I could not find 
> an example or sample of it being disabled in a libvirt XML file.  Nor 
> does there appear to be a schema (xsd or dtd) for the libvirt file 
> format, which might have had an hpet element or attribute.
>
> Ideally, is there a way to disable HPET in the BIOS for a specific VM, 
> and not all VMs.  Thank you.

If you are running libvirt 0.8.0 or newer, and if your qemu-kvm supports 
the -no-hpet option (check the output of "qemu-kvm --help"), you can add 
the -no-hpet option for qemu-kvm for a particular domain by editing the 
domain's XML (with "virsh edit domainname") and adding

<timer name='hpet' present='no'/>

to the "clock" section. It will end up looking something like this:


<clock offset='utc'>
<timer name='hpet' present='no'/>
</clock>
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