[CentOS-virt] Are xen and centos incompatible?

Thu Jun 12 17:38:30 UTC 2014
Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>

> Hm, xen kinda makes the cpus and their power management invisible, too:
> root at heimdall:~# xenpm get-cpufreq-para
> [CPU0] failed to get cpufreq parameter
> [...]
> root at heimdall:~# xenpm  get-cpufreq-states
> root at heimdall:~# 
> So I guess it could as well make it so that lspci doesn't show
> passed-out devices.

I am wondering if you are using an older kernel. The xen-acpi-processor
driver should be loaded which would give the C and P states to the
hypervisor. Which in turn would result in those above commands
providing the right data.

> BTW, getting some info in dmesg might be nice, like a message saying
> "xen-pciback: device 06:00.0 can be passed through to guests".  We could

You just need to boot with 'debug'  - and it should tell you that
a device is being assigned to another guest (when assigning). Also
at bootup it will tell you that it is seizinging.

Just do 'dmesg | grep pciback' and you will get it.

> actually see right away if it did work or not.  That a device disappears
> isn't too great as indication, especially not when lspci still lists it.
> Of course, you could use the command (which I don't remember) to show
> devices that can be passed through.  But that may just work as well as

Such as xl or xm pci-list-assignable?

> 'xenpm get-cpufreq-states':  Apparently, there aren't any CPUs ...

See if xen-acpi-processor is loaded or built in.
> -- 
> Knowledge is volatile and fluid.  Software is power.
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