I hate dual-booting between Windows when I want to play a game and Linux when I need to work. I don't fancy running Linux in a VM and Wine almost never works for me. So, I'm thinking about buying a new mainboard and CPU that is compatible with Xen's VGA passthrough and HVM virtualization.

I want to be able to switch between the Linux Dom0 and Windows DomU with ease, but the problem is I need two GPU's and have only one monitor.

Right now I have a nVidia GTX 260 in my PC, but I also have a Radeon 4850 sitting in my closet that I was going to sell.

My question is, can I salvage the Radeon card to run the Dom0 and have the nVidia card run the DomU while having some kind of device/software to connect them a single monitor? Power supply and airflow issues aside.

If not, what would you suggest? Is this even possible?

  • I would use a KVM to switch between the two – user123063 Mar 15 '12 at 2:10

The easiest thing to do, if your monitor has multiple high-resolution inputs, is to connect your monitor to both graphics cards. Then, when you need to swap your display to your other VM, you just hit the button on your monitor that changes what input it displays; ie, DVI to DVI on your windows box to one graphics card, HDMI to HDMI on your linux box to the other graphics card. Substitute converters where necessary (DVI to HDMI, or HDMI to DisplayPort, etc depending on your monitor inputs and graphic card outputs). Then you can use something like Synergy for your input control.

A KVM switch would be preferable to this scenario, as you could have Audio, Video, and Keyboard/Mouse input change from VM to VM with a simple keybinding.

  • This is a really late answer, but I am going to use a KVM switch. – user489481 Sep 5 '14 at 1:33

Once Dom0 booting, you can launch Windows DomU with a SDL window. So you don't need any switch.

Your Windows config file must have:


"yy:zz.n" is the PCI ID of the VGA graphics adapter, you can check it with "lspci -v" in Dom0.

But for playing, I'm not sure the performance will be there.


From what I gathered in recent researches, it is not possible to hotplug/reassign the VGA passthrough while a HVM is running. Therefore, you would assign one gpu for each OS, one for the Dom0 and one for the DomU. Unplugging the monitor from one graphic card and plugging it to the other should do the trick for not having to dual boot. I might experiment all this soon with new hardware with a Vt-d enabled cpu and motherboard. I would like to have a keybinding to easily assign a single graphic card to a VM (aka hotplugging) but according to xensource it is not possible yet.


What you want is a DVI switch. Search Amazon, eBay, etc. There are tons of them that let you share multiple video sources with one monitor.

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