[clug] KVM & Virt-Manager

Rodney Peters rodneyp at iinet.net.au
Wed Apr 13 06:51:16 UTC 2016

On Tuesday 12 Apr 2016 21:44:25 George at Clug wrote:
>     Does anyone use KVM and Virt-Manager to host Guest VMs on their
> Linux desktop computer?   I have been for the past six or so months.
> I ha​ve found that KVM as a Hypervisor works quite well. However
> when I create a Cinnamon Guest and log in, the system reports "Running
> in software rendering mode", "Cinnamon is currently running without
> video hardware acceleration and, as a result, you may observe much
> higher than normal CPU usage".
> Now I suspect few people bother to run guest VMs with a Desktop
> Environment, and in particularly with Cinnamon or with Gnome. 
> Hopefully though there will be at least a few people who do (or at
> least have tried).
> As per one of my previous emails, VMware Workstation can emulate video
> hardware acceleration good enough for Cinnamon to believe it is
> running on true hardware.
> Searching the Internet I have found reports that suggest this is not
> currently possible, some reports suggest it is with virgil3d, but as
> yet this project is not packaged with Debian as yet, and then there
> are reports of "gl='yes'" and "accel3d='yes' accel2d='yes".
> https://en.wikipedia.org/wiki/Kernel-based_Virtual_Machine
> "Video card [1] Cirrus CLGD 5446 PCI VGA card, dummy VGA card with
> Bochs [2] VESA [3] extensions, or Virgil [4] as a virtual 3D GPU"
> I have tested the below two configurations for my test Guest VM, but
> they do not appear to work the way I expect them. Have you any
> experience with these settings and knowledge of what they actually do,
> and any conditions (hardware or software) that must be met for them to
> be used, please do let us know.
> If you do not understand why I want to run a Cinnamon Linux
> installation as a guest VM, do not worry, it is just a particular idea
> that I have for testing various GUIs (i.e. Desktop Environments
> without needing separate physical computers.
> Regards, George.
Hi George.

Further to my previous reply, I find that there is hardware pass-through for 
kvm.  see 

Although I can load  the vfio-pci driver it has no effect - my mainboard is too 
old to support IOMMU.

Note that shared video hardware is not (yet ?) supported and that you would 
need two or more video cards if you are not running headless or want more than 
one VM.

Would be interested to know how you fare - I might yet get an excuse for a 
mainboard upgrade :-)



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