[Fedora-xen] xen to kvm migration question

Avi Kivity avi at qumranet.com
Sun Jun 29 13:54:53 UTC 2008

Richard W.M. Jones wrote:
> On Fri, Jun 27, 2008 at 05:56:37PM -0400, Paul Wouters wrote:
>> Although I was very happy with xen, it seems xen is losing out and kvm
>> is the way to go. I had two migration questions that I couldn't find
>> answers for.
>> 1) Does kvm also run with para_virt (eg without VT capable cpu, but also
>>    just to be slightly more effecient). virt-manager only gave me a qemu
>>    option on my old amd64 cpu.
> KVM requires a hardware virt-capable CPU.  These are quite common,
> (if your CPU was made within the last two years or so)
> but note there are at least two major 'generations' of virt
> technology in CPUs.  In particular very new CPUs from both Intel
> and AMD support some form of virtualized page tables, which can be
> very beneficial.  Intel describes them here:
> http://www.intel.com/technology/itj/2006/v10i3/1-hardware/8-virtualization-future.htm
> [Question: does EPT / NPT only affect 32 bit?]

No, it's applicable to both 32- and 64- bit guests.

The KVM NPT implementation does not work for 32-bit nonpae hosts (it 
will fall back to not using NPT), so if you have a recent AMD processor 
and you are using a 32-bit installation, use the pae kernel for best 

The kvm NPT and EPT implementations were introduced in Linux 2.6.26.

error compiling committee.c: too many arguments to function

More information about the Fedora-xen mailing list