On Tue, Apr 14, 2009 at 09:23:35PM -0400, Gerry Reno wrote: > Gerrit Slomma wrote: > >Gerry Reno schrieb: > >> > >>I have a 64-bit host that is running a 32-bit OS (Fedora 10). > >>(...) > >># virsh nodeinfo > >>CPU model: i686 > >>(...) > >>Shouldn't the host arch have been detected and identified as x86_64? The host arch reflects the arch of the "hypervisor". In Xen where you have a separate Hypervisor and Dom0 OS, you can in theory use a 64-bit hypervisor and 32-bit Dom0 and still run 64-bit guests. In KVM, the host OS *is* the hypervisor, so you have to run a 64-bit host OS if you want 64-bit guests. ....unles you want to run really slow QEMU 64-bit emulation, but I'm pretty sure you don't want todo that :-) > > > >As stated by you in the beginning: You are running a 32-bit OS. > >You can't have more bit than the OS is providing you. > >/usr/bin/qemu-system-x86_64 alwas shows x86_64, even on my Core Duo. > > Is it allowed to run x86_64 guest OS on x86_64 physical machine with x86 > (32-bit) host OS? Technically it is not the host OS arch that matters, but rather the hypervisor arch. Since KVM is built-in to the Linux host OS, you need a 64-bit host OS. Really you don't want to rnu 32-bit host OS under any circumstances. 32-bit has horrible memory limitations, horrible register limitations and should be left to die an ungraceful death. 32-bit guests are fine if you so wish, but just say no to 32-bit hosts, particularly since you have 64-bit CPUs Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list