[Qemu-devel] Re: [PATCH 4/4] KVM: Rework of guest debug state writing

[Marcelo Tosatti]

On Thu, Feb 04, 2010 at 01:33:50AM +0100, Jan Kiszka wrote:
> Marcelo Tosatti wrote:
> > On Wed, Feb 03, 2010 at 10:29:45PM +0100, Jan Kiszka wrote:
> >> So far we synchronized any dirty VCPU state back into the kernel before
> >> updating the guest debug state. This was a tribute to a deficit in x86
> >> kernels before 2.6.33. But as this is an arch-dependent issue, it is
> >> better handle in the x86 part of KVM and remove the writeback point for
> >> generic code.
> > 
> > Jan,
> > 
> > This patch breaks migration.
> 
> Can you elaborate what you did? I can't reproduce, and I do not see any
> conceptual issue (given that guest debugging conflicts with migration
> anyway).

kvm-autotest fails (migration only, install is ok, both Linux and Win
guests). Not sure why, perhaps the unconditional KVM_SET_GUEST_DEBUG
corrupts state somehow? 

Tested with io thread enabled.