libvirt users - Feb 2021 - Upgrading the host

On 2/16/2021 12:51 AM, Michal Privoznik wrote:
> On 2/12/21 2:10 AM, Marcin Struzak wrote:
> [...]
>
>> ?3. Anything else I should worry about or prepare ahead?
>
> Not strictly related to libvirt, but machine types might be problem. I 
> guess qemu will be upgraded too and in general the machine type you're 
> using for a domain might not be available in upgraded qemu.
Correct, it looks like qemu will go from 1.6.2 to
4.2.1...
>
> You can view supported machine types by running 'virsh
capabilities'
> with upgraded qemu.
machine is pc-i440fx-1.6 in all my domains.? Is there a simple way to 
figure out if that's supported in libvirt 6.1.0 (without installing
it)?
>
> Good luck!
>
> Michal
>
Thank you for a quick & detailed answer.

--Marcin

On 2/17/21 2:45 AM, Marcin Struzak wrote:
> On 2/16/2021 12:51 AM, Michal Privoznik wrote:
>> On 2/12/21 2:10 AM, Marcin Struzak wrote:
>> [...]
>>
>>> ?3. Anything else I should worry about or prepare ahead?
>>
>> Not strictly related to libvirt, but machine types might be problem. I 
>> guess qemu will be upgraded too and in general the machine type
you're
>> using for a domain might not be available in upgraded qemu.
> Correct, it looks like qemu will go from 1.6.2 to 4.2.1...
>>
>> You can view supported machine types by running 'virsh
capabilities'
>> with upgraded qemu.
> machine is pc-i440fx-1.6 in all my domains.? Is there a simple way to 
> figure out if that's supported in libvirt 6.1.0 (without installing
it)?
It's not libvirt who has say in machine types. Libvirt treats machine 
type as an opaque string. But I can see that pc-i440fx-1.6 is still 
available even with the latest QEMU release:

# /usr/bin/qemu-system-x86_64 -version
QEMU emulator version 5.2.0

# virsh capabilities | grep pc-i440fx-1.6
       <machine maxCpus='255'>pc-i440fx-1.6</machine>
       <machine maxCpus='255'>pc-i440fx-1.6</machine>

So you are safe on that front.

Michal