[pve-devel] Snapshots / Qemu Version

[Alexandre DERUMIER]

> You have: 
> pc-i440fx-1.4 Standard PC (i440FX + PIIX, 1996) 
> and 
> pc-q35-1.4 Standard PC (Q35 + ICH9, 2009) 
>

Yes, q35 is not yet ready, but in the future (maybe next year), it should become the default.
It's emulated pci-express slots and new things.



> I think the correct way would be: 
> 1.) always pass the -machine parameter so we "know" our default 
> 2.) save the current machine parameter in config 
> 3.) when creating a snapshot save this value too 

I think for snapshot, indeed we should save qemu version.

>>Same problem occours if we have a running VM (qemu 1.4) and we migrate 
>>this one to another server running 1.X. We also need to set the machine 
>>parameter here.

For live migration, I think we can detect with qmp the qemu version, the pass the parameter to the target vm.
(So it can work with existing vm configs, and we don't need to update the config file when we update qemu).
Maybe this should be optionnal, because I like to use live migrate to update to new qemu version, without restarting the vm. 
I personnaly never have had problem with live migration from lower to higher qemu version. 
 
----- Mail original ----- 

De: "Stefan Priebe" <s.priebe at profihost.ag> 
À: "Alexandre DERUMIER" <aderumier at odiso.com> 
Cc: pve-devel at pve.proxmox.com 
Envoyé: Samedi 25 Mai 2013 12:48:28 
Objet: Re: [pve-devel] Snapshots / Qemu Version 

Am 25.05.2013 12:45, schrieb Stefan Priebe: 
> Am 25.05.2013 08:17, schrieb Alexandre DERUMIER: 
>> maybe does it work by starting the qemu with "qemu -machine pc-1.X" 
>> works ? 
> 
> Yes this works FINE! But there is no common pc-1.4 anymore. 
> 
> You have: 
> pc-i440fx-1.4 Standard PC (i440FX + PIIX, 1996) 
> and 
> pc-q35-1.4 Standard PC (Q35 + ICH9, 2009) 
> 
> It depends which chipset you had used before. 
> 
> I think we def. need to implement this into proxmox. But what is about 
> parameter changes for kvm process? 
> 
> I think the correct way would be: 
> 1.) always pass the -machine parameter so we "know" our default 
> 2.) save the current machine parameter in config 
> 3.) when creating a snapshot save this value too 

Same problem occours if we have a running VM (qemu 1.4) and we migrate 
this one to another server running 1.X. We also need to set the machine 
parameter here. 

Stefan