On 01/15/2013 11:29 AM, Paolo Bonzini wrote:
> Il 15/01/2013 04:45, Cole Robinson ha scritto:
>> Libvirt always specifies an explicit machine type and carries it for the life
>> of the VM. What we want is for 'qemu-kvm-1.2 -M pc-1.2' to migrate seamlessly
>> into 'qemu-1.3+ -M pc-1.2' without the user or libvirt having to change
>> machine type.
>>
>> So what we want to carry in Fedora is:
>>
>>
>> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
>> index aa3e7f4..b8f5f8a 100644
>> --- a/hw/pc_piix.c
>> +++ b/hw/pc_piix.c
>> @@ -315,6 +315,10 @@ static QEMUMachine pc_machine_v1_3 = {
>> .driver = "VGA",\
>> .property = "mmio",\
>> .value = "off",\
>> + },{\
>> + .driver = "cirrus-vga",\
>> + .property = "vgamem_mb",\
>> + .value = stringify(8),\
>> }
>>
>> static QEMUMachine pc_machine_v1_2 = {
>>
>>
>> That sticks the cirrus compat block on the end of PC_COMPAT_1_2, which should
>> fix cirrus migration from qemu-kvm for all machine types <= pc-1.2. Obviously
>> this isn't suitable for upstream but we can hide it behind something like
>> ./configure --qemu-kvm-migrate-compat
>
> Let's look at the source to reconstruct the changes.
>
> In qemu-kvm-0.15.1 (Fedora 16), file hw/vga_int.h, we had
>
> #define VGA_RAM_SIZE (16 * 1024 * 1024)
>
> In qemu-0.15.1, same file, we had
>
> #define VGA_RAM_SIZE (8192 * 1024)
>
> The same holds all the way back to 0.9, which had them in hw/pc.h.
>
> hw/vga-pci.c in qemu-kvm-1.2 and qemu-1.2 had both this line:
>
> DEFINE_PROP_UINT32("vgamem_mb", PCIVGAState, vga.vram_size_mb, 16),
>
> but hw/cirrus_vga.c had respectively:
>
> #define VGA_RAM_SIZE (16384 * 1024)
> #define VGA_RAM_SIZE (8192 * 1024)
>
> So the right patch for downstreams that used qemu-kvm is this:
>
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 85529b2..c29ea0d 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -410,22 +410,6 @@ static QEMUMachine pc_machine_v1_2 = {
> .property = "param_change",\
> .value = "off",\
> },{\
> - .driver = "VGA",\
> - .property = "vgamem_mb",\
> - .value = stringify(8),\
> - },{\
> - .driver = "vmware-svga",\
> - .property = "vgamem_mb",\
> - .value = stringify(8),\
> - },{\
> - .driver = "qxl-vga",\
> - .property = "vgamem_mb",\
> - .value = stringify(8),\
> - },{\
> - .driver = "qxl",\
> - .property = "vgamem_mb",\
> - .value = stringify(8),\
> - },{\
> .driver = "virtio-blk-pci",\
> .property = "config-wce",\
> .value = "off",\
> diff --git a/hw/cirrus_vga.c b/hw/cirrus_vga.c
> index 9bef96e..8c94428 100644
> --- a/hw/cirrus_vga.c
> +++ b/hw/cirrus_vga.c
> @@ -2975,7 +2975,7 @@ static int pci_cirrus_vga_initfn(PCIDevice *dev)
>
> static Property pci_vga_cirrus_properties[] = {
> DEFINE_PROP_UINT32("vgamem_mb", struct PCICirrusVGAState,
> - cirrus_vga.vga.vram_size_mb, 8),
> + cirrus_vga.vga.vram_size_mb, 16),
> DEFINE_PROP_END_OF_LIST(),
> };
>
>
> i.e. use 16 MB for all machine types and all cards. The latter should
> probably be pushed into 1.4 with compat properties for 1.3. At this
> point, you need to remove the compat property as in the pc_piix.c above.
>
Thanks for the analysis Paolo, here's the final patch I used:
http://pkgs.fedoraproject.org/cgit/qemu.git/tree/0004-Fix-migration-compat-with-qemu-kvm.patch
Thanks,
Cole
