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Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm |
Date: |
Wed, 24 Sep 2014 10:05:19 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
Alex Bligh <address@hidden> 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"?
> 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().
> * 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?
> The above monkey-patching must be done between the selection of
> the MachineClass and the processing of the machine parameters
> (on the one hand) and the processing of the compat_props list
> and the globals on the command line. To do this I
> have added
> an earlyinit function to MachineState and QEMUMachine.
>
> I developed this on qemu 2.0 but have forward ported it (trivially)
> to master. My testing has been on a VM live-migrated-to-file from
> Ubuntu Precise qemu-kvm 1.0.
>
> I have given this a moderate degree of testing but it could do
> with more.
>
> Note that certain hardware devices (including QXL) will not
> migrate properly due to a fundamental difference in their internal
> state between versions.
>
> Also note that (as expected) migration from qemu-2.x to qemu-1.0
> will not work, even if the machine types are the same.
>
> 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.
- [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm, Alex Bligh, 2014/09/22
- [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm, Alex Bligh, 2014/09/22
- Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm, Michael S. Tsirkin, 2014/09/28
- Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm, Alex Bligh, 2014/09/28
- Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm, Markus Armbruster, 2014/09/29
- Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm, Michael S. Tsirkin, 2014/09/29
- Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm, Alex Bligh, 2014/09/29
- Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm, Serge E. Hallyn, 2014/09/29
Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm,
Markus Armbruster <=
Re: [Qemu-devel] [PATCH v4] Add machine parameter qemu-kvm-migration for live migrate compatibility with qemu-kvm, Michael Tokarev, 2014/09/24