Re: [Qemu-devel] Re: [Bug 596106] Re: kvm to emulate 64 bit cpu on 32 bit host

[Jamie Lokier <jamie@shareable.org>]

Paolo Bonzini wrote:
> On 06/19/2010 03:01 PM, Natalia Portillo wrote:
> >VMWare is able to do it, we should be able.
> 
> They do it like TCG does it, not like KVM.

I heard rumours VMWare use KVM-style chip virtualisation when running
a 64-bit guest on a 32-bit host kernel on 64-bit hardware.

If true, that makes particular sense for Windows host users, who can't
just drop in a 64-bit host kernel without breaking their userspace
thoroughly.  (If it was that easy, 64-bit Windows wouldn't use
a surruptitious VM to run 32-bit apps :-).

It seems like a good way for Windows users to run a single 64-bit app
on an otherwise 32-bit system that's working fine.

On Linux hosts I would expect you can drop in a 64-bit kernel, while
continuing to run a 32-bit userspace.  But I don't know if (a) that's
entirely true, and (b) if distro packaging blocks that sort of thing
from being easy.

Unfortunately even that doesn't help people who just want to run a
64-bit VM as an ordinary user and aren't permitted to change their
Linux host kernel, e.g. a shared system, or some rented servers.

-- Jamie