On Wed, 2012-06-20 at 01:11 +0200, Juan Quintela wrote: > > > I am confident I can come up with something as far as the kernel and > > qemu <-> kernel interface goes. I need to get my head around the details > > on how to implement that two stage save process in qemu though and the > > corresponding restore which will need to read both snapshots and apply > > the diff before shooting it back to the kernel. > > > > BTW. Does migration in pure qemu (full system emu) works similarily, ie, > > two stage ? If it does I can easily prototype everything there. > > It does, but I have no clue how the hashed page tables are implemented > on ppc, i.e. if there is anything specific for bare metal. Alex?
We support the paravirtualized -M pseries in full emu as well, in which case the hashed page table is handled by qemu itself who implements the H_ENTER & co hypercalls. So it's very similar, except that qemu doesn't have to ask the kernel to get a snapshot :-) So I can flush out the storage format and two stage process inside qemu, and then bother with the kvm/kernel interface. Normal "bare metal" operation in qemu (or even KVM "PR") doesn't require this as in that case the hash table is just a normal part of the guest memory, it's only an issue when doing paravirtualized guest such as pseries (aka PAPR). Cheers, Ben.