Re: [PATCH] KVM: Veirfy memory slot only for readability

Sasha Levin
2011-12-04T17:29:35Z

On Sun, 2011-12-04 at 18:53 +0200, Avi Kivity wrote:
> On 12/02/2011 07:46 AM, Sasha Levin wrote:
> > > Do you want to create read only memory slots for kvm tool?
> >
> > What KVM tool currently does is copy the kernel into guest memory and
> > run it from there. An idea raised recently was instead of copying it we
> > should mmap it into the memory to reduce footprint.
> >
> > This is why I'm looking into adding a read only memory slot. The KVM
> > code doesn't have to know it's read only.
>
> The kernel will patch itself very early. You need to use MAP_PRIVATE
> (and thus have a read/write area). It will be interesting to see what
> fraction of the memory is modified.
>
> Note that mapping will remove benefits like huge page support, and that
> you can get page sharing by using ksm. Still, it's interesting to see
> where this goes.

Why would I lose hugepage if the kernel gets it's own memory slot?

--

Sasha.