On 4/29/22 15:36, Jason Gunthorpe wrote: > On Fri, Apr 29, 2022 at 03:27:00PM +0100, Joao Martins wrote: > >>> We've made a qemu patch to allow qemu to be happy if dirty tracking is >>> not supported in the vfio container for migration, which is part of >>> the v2 enablement series. That seems like the better direction. >>> >> So in my auditing/testing, the listener callbacks are called but the dirty ioctls >> return an error at start, and bails out early on sync. I suppose migration >> won't really work, as no pages aren't set and what not but it could >> cope with no-dirty-tracking support. So by 'making qemu happy' is this mainly >> cleaning out the constant error messages you get and not even attempt >> migration by introducing a migration blocker early on ... should it fetch >> no migration capability? > > It really just means pre-copy doesn't work and we can skip it, though > I'm not sure exactly what the qemu patch ended up doing.. I think it > will be posted by Monday > Ha, or that :D i.e. Why bother checking if there's dirty pages periodically when we can just do at the beginning, and at the end when we pause the guest(and DMA). Maybe it prevents a whole bunch of copying in the interim, and this patch of yours might be a improvement.
