Markus, On 24 Sep 2014, at 09:05, Markus Armbruster <arm...@redhat.com> wrote:
> Alex Bligh <a...@alex.org.uk> writes: > >> This patch series adds inbound migrate capability from qemu-kvm version >> 1.0. The main ideas are those set out in Cole Robinson's patch here: >> http://pkgs.fedoraproject.org/cgit/qemu.git/tree/0001-Fix-migration-from-qemu-kvm.patch?h=f20 >> however, rather than patching statically (and breaking inbound >> migration on existing machine types), I have added a new machine >> parameter (qemu-kvm-migration) which when turned on affects the pc-1.0 >> machine type. Usage: >> -machine pc-1.0,qemu-kvm-migration=on > > Forgive me if this has been discussed already: why not simply a separate > machine type "pc-1.0-qemu-kvm"? That's what v2 of the patch set does (and I prefer v2). However, mst wanted it done this way. > >> Three aproaches are taken: >> >> * cirrus-vga.vgamem_mb defaults to 16 rather than 8. In order to >> keep -global cirrus-vga.vgamem_mb working even with >> qemu-kvm-migration=on, this is monkey-patched into the default >> value of the MachineState structure's compat_props >> list. > > This part fires only for pc-1.0, because it's in > pc_early_init_pci_1_0(). Yes, intentional. I should have noted that. That's because qemu-kvm-migration=on the VRAM change was designed to work only with pc-1.0. I haven't looked at trying to make other (older) qemu-kvm machine migrations work, but (with the stuff below), I would guess it would work with the appropriate command line options for VRAM size. Obviously I could put early init elsewhere. >> * In hw/timer/i8254_common.c, the VMSTATE_UINT32_TEST macro >> is used to test the version for the irq_disable flags, >> allowing version 3 or more, or version 2 for an inbound >> migrate from qemu-kvm (only). >> >> * In hw/acpi/piix4.c, qemu-kvm incorrectly uses version 2 for >> a version 3 structure, causing acpi_load_old to be used. >> acpi_load_old detects this situation based on the machine type >> and restarts the attempt to load the vmstate using a >> customised VMStateDescription. The above cleaner approach is >> unavailable here. > > These parts apply to all machine types, don't they? They apply only when qemu-kvm-migration=on is selected, but to any machine type; however machine types newer than pc-1.0 will be exporting v3 I think anyway. >> Changes since v1: >> * Do not use a machine type, use a machine parameter. > > Okay, it has been discussed already. I'd appreciate a brief recap all > the same. See above. I preferred the machine type. But I got to learn more about QOM on the way :-) -- Alex Bligh
