* Steven Sistare (steven.sist...@oracle.com) wrote: > On 5/20/2021 9:00 AM, Dr. David Alan Gilbert wrote: > > Hi Steven, > > I'd like to split the discussion into reboot and restart, > > so I can make sure I understand them individually. > > > > So reboot mode; > > Can you explain which parts of this series are needed for reboot mode; > > I've managed to do a kexec based reboot on qemu with the current qemu - > > albeit with no vfio devices, my current understanding is that for doing > > reboot with vfio we just need some way of getting migrate to send the > > metadata associated with vfio devices if the guest is in S3. > > > > Is there something I'm missing and which you have in this series? > > You are correct, this series has little special code for reboot mode, but it > does allow > reboot and restart to be handled similarly, which simplifies the management > layer because > the same calls are performed for each mode. > > For vfio in reboot mode, prior to sending cprload, the manager sends the > guest-suspend-ram > command to the qemu guest agent. This flushes requests and brings the guest > device to a > reset state, so there is no vfio metadata to save. Reboot mode does not call > vfio_cprsave. > > There are a few unique patches to support reboot mode. One is > qemu_ram_volatile, which > is a sanity check that the writable ram blocks are backed by some form of > shared memory. > Plus there are a few fragments in the "cpr" patch that handle the suspended > state that > is induced by guest-suspend-ram. See qemu_system_start_on_wake_request() and > instances > of RUN_STATE_SUSPENDED in migration/cpr.c
Could you split the 'reboot' part of separately, then we can review that and perhaps get it in first? It should be a relatively small patch set - it'll get things moving in the right direction. The guest-suspend-ram stuff seems reasonable as an idea; lets just try and avoid doing it all via environment variables though; make it proper command line options. Dave > - Steve > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
