Re: [QUERY] lguest64

[Alex Elsayed <eternaleye@gmail.com>]

Ramkumar Ramachandra wrote:

> H. Peter Anvin wrote:
>> UML, lguest and Xen were done before the x86 architecture supported
>> hardware virtualization.
> 
> [...]
> 
>> but on KVM-enabled hardware KVM seems
>> like the better option (and is indeed what libguestfs uses.)
> 
> While we're still on the topic, I'd like a few clarifications. From
> your reply, I got the impression that KVM the only mechanism for
> non-pvops virtualization.  This seems quite contrary to what I read on
> lwn about ARM virtualization [1]. In short, ARM provides a "hypervisor
> mode", and the article says
> 
>   "the virtualization model provided by ARM fits the Xen
> hypervisor-based virtualization better than KVM's kernel-based model"
> 
> The Xen people call this "ARM PVH" (as opposed to ARM PV, which does
> not utilize hardware extensions) [2]. Although I wasn't able to find
> much information about the hardware aspect, what ARM provides seems to
> be quite different from VT-x and AMD-V. I'm also confused about what
> virt/kvm/arm is.
> 
> Thanks.
> 
> [1]: http://lwn.net/Articles/513940/
> [2]: http://www.xenproject.org/developers/teams/arm-hypervisor.html

ARM's virtualization extensions may be a more *natural* match to Xen's 
semantics and architecture, but that doesn't mean that KVM can't use it. LWN 
explains the details far better than I can: https://lwn.net/Articles/557132/

virt/kvm/arm is an implementation of KVM (the API) that takes advantage of 
ARM's virtualization extensions.