Re: [Qemu-devel] vm state save/restore question

[Alexander Graf]

On 19.06.2012, at 23:13, Benjamin Herrenschmidt <address@hidden> wrote:

> On Tue, 2012-06-19 at 23:00 +0200, Alexander Graf wrote:
>> How is the problem different from RAM? It's a 16MB region that can be
>> accessed by the guest even during transfer time, so it can get dirty
>> during the migration. But we only need to really transfer the last
>> small delta at the end of the migration, right?
> 
> Because with -M pseries it's not mapped into guest space but instead is
> a chunk of physically contiguous memory accessed directly in real mode
> by KVM. So no dirty tracking here.
> 
> We could keep track manually maybe using some kind of dirty bitmap of
> changes to the hash table but that would add overhead to things like
> H_ENTER.

Only during migration, right?

Alex