Re: [libvirt] libvirt arch detection on x86_64 host
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
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