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Theoretischer

Member

Registered: 2023-05-05

Posts: 8

[Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

Hi, so I have no idea if it is even possible to do what i am planning. So I use my machine for everything (gaming, browsing, etc) and i looked into setting up a virtual machine with GPU pass through. My problem is that my main board only has 2 display inputs and I have 3 monitors. So my idea was it (and someone told me that it should be possible) to configure xorg to render the third monitor connected to the dGPU on the iGPU so that no process runs on the dGPU (so it can be passed to the VM). If someone knows how to do it or has another idea, I would appreciate it. Or when someone knows an adapter or something like that so i can plug the third monitor into the motherboard would also be ok (I don't have a thunderbolt sadly)

I use KDE and wayland
my iGPU is amd
my dGPU is NVIDIA with proprietary drivers

If this is the wrong place to post this, I am sorry, I have never used the forum before. Just tell me and i will delete my post here and post it somewhere else

Last edited by Theoretischer (2023-05-08 13:51:50)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,197

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

You can't do that afaik (because you can't magic away the fact that your output is attached to the dedicated gpu and completely bypass it without it being initialized on the host OS in any way). But you can (... and must, generally) use the monitor attached to the dGPU to host the passthrough VM.

Last edited by V1del (2023-05-05 17:13:02)

Theoretischer

Member

Registered: 2023-05-05

Posts: 8

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

Oh, that is sad to hear. Do you know any other way to use a third monitor with that setup? Or can i maybe make some scrips, because when i just plug in the third monitor into the gpu and reboot my third monitor shows something but an xorg process runs on the gpu so i can't passthrough

Edit: I was planning on not doing to VFIO on boot method, so that i am initializing the drivers only when i need them, that's why i thought it would be possible

Last edited by Theoretischer (2023-05-05 17:30:55)

Lone_Wolf

Administrator

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 15,041

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

My problem is that my main board only has 2 display inputs and I have 3 monitors

What is the brand, model and type of the mainboard and monitors used ?

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Theoretischer

Member

Registered: 2023-05-05

Posts: 8

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

My problem is that my main board only has 2 display inputs and I have 3 monitors

What is the brand, model and type of the mainboard and monitors used ?

The board is MSI MAG B650 Tomahawk WIFI, and 2 of my monitors are LG and one iiyama but i don't understand how the monitors would matter.

Last edited by Theoretischer (2023-05-07 11:54:03)

Lone_Wolf

Administrator

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 15,041

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

VGA , DVI , HDMI , DP all have multiple versions and capabilities.

Your motherboard has 1 HDMI 2.1 and 1 DP 1.4 connector . 
DisplayPort 1.2 and later support a technique called Multi-Stream Transport (often referred to as daisychaining) that allows several monitors to use one connector .

If atleast 2 of your monitors support DP 1.2+ , you can connect those to the DP connector on your mobo and don't need a 3rd connector .

Last edited by Lone_Wolf (2023-05-07 12:12:34)

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Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

clean chroot building not flexible enough ?
Try clean chroot manager by graysky

Theoretischer

Member

Registered: 2023-05-05

Posts: 8

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

Sadly only one has displayport, but would a DP to hdmi convertor work?

progandy

Member

Registered: 2012-05-17

Posts: 5,311

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

I think that could work if the converter supports it and your monitor has a daisy-chain port. There are also DP splitters / MST hubs, look for one that supports DP 1.4 and has 2-3 hdmi outputs I think. You'll be limited to 4K@60Hz per monitor or so.

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Theoretischer

Member

Registered: 2023-05-05

Posts: 8

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

Ok i found a splitter from DP 1.4 to two 60hz hdmi, which won't be a problem because i can just use the hdmi output on the motherboard for 2k 144hz. I guess i will go with that option then. But are there some convertors that only work with windows or are all linux compatible?

Lone_Wolf

Administrator

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 15,041

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

It should work on every OS since these device operate on hardware level.

Does the description/specification mention anything about drivers or software ? If yes, that's a bad sign.
Maybe you could post a link to the device you're considering ?

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Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

clean chroot building not flexible enough ?
Try clean chroot manager by graysky

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,197

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

You might also have to be weary that the splitter actually allows distinct signals, otherwise you might be only be able to mirror the output. But focusing on DP 1.4 might be the deal to avoid that

Theoretischer

Member

Registered: 2023-05-05

Posts: 8

Re: [Solved]Configure Xorg to use iGPU to render monitor connected to dGPU

Yep already found some that let you connect monitors