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Comment by mongol | Hacker News Reader

What does this do that regular KVM + Qemu does not?

It provides bare metal access to the entire hardware stack. So for instance you could run Linux via your integrated GPU (the one on many consumer CPUs) while passing through your dedicated GPU to the Windows VM.

This is how I "gamed on Linux" from 2018~2020 when I ran Ubuntu as my primary OS. It's incredibly finicky to set up (shocker, I know!) but if you're able to get it working it's truly amazing. Talking like 1% performance loss in AAA games in that virtual machine on the GPU.

As for me, I abandoned Ubuntu (and Linux, I did try other distros!) in early 2020. I was tired of juggling my home setup just to relax. In a move unpopular with the Slashdot crowd from 1996, I went back to Windows as my host OS.

Can you elaborate on the finickiness of it? What kind of "fixes" you needed to do, and how often really, and with a cause or just random with no precursors?

Everything about it is fickle. Motherboards and USB controllers present themselves different from maker to maker, and SKU to SKU. Any change in your hardware -- including plugging in something like a USB device -- sets off a chain of fighting the host OS and virtual machines for who gets to use that device, who gets to see that device at all, and the drivers needed for the hardware.

No one is making user software with VFIO in mind. You will get random apps that do not launch in your virtual machine despite everything else running smoothly.

You're screwing with it near daily, certainly weekly. Need to update a driver, such as your GPU on the virtual machine? May god have mercy on your soul that everything works after, or that you can even get the host OS to deal with the GPU correctly at all.

I can sort of tell you haven't really read up on one of these setups because you seem incredulous that running Windows inside Linux is somehow finicky.

It's not ready for prime time, period.

Thanks for the detailed response.

I personally don't mind the semi-daily tinkering with my config, but if even plugging in a USB might break things then it does sound petty unreliable.

> I can sort of tell you haven't really read up on one of these setups because you seem incredulous that running Windows inside Linux is somehow finicky.

Ouf. You have a great imagination, but I think you'd do better to put it into writing fiction or something like that. I asked you to provide details on your comment, didn't make any statements on whether it is indeed finicky or not, I run many Windows vms on linux but never with VFIO. Your snide remarks reflect nothing more than your lack of self-esteem.

Apart from some initial issues it’s mostly been set it and forget it for me? I’ve been running a VFIO setup since 2017.

GPU driver updates haven’t broken anything in years. Nvidia actually made their drivers more passthrough friendly not too long ago (No longer need to spoof the vendor ID).

I have not had any compatibility issues with software either. I know there are some multiplayer games that specifically check if you are running in a VM and refuse to run. It’s a handful of games though and I don’t play those.

Just use Proton. Install games from Steam directly.

Atleast right now, most anticheat software aren't available for Linux, You need a Windows kernel for them to run.

This can however change as Steam plans to use SteamOS (based on Arch) as their primary OS on the SteamDeck.

I hope they make it opt in. I don’t really want an anti cheat snooping around my Linux system without my knowing

yup, though since they will require administrative permissions, I don't think valve will go around making you install it unless you play the specific game. Also I don't really understand how GPLv2 and kernel modules work, but I wonder if AntiCheats would be forced to open source themselves? Probably not honestly.

Edit: If anyone wanna read Linus's thoughts on it [1]. TL;DR It's a legal gray area.

[1]. https://yarchive.net/comp/linux/gpl_modules.html

And only a minority of games do require anticheat.

This is a non-answer. Steam is not and should not be the sole source of video games on PC. This is a workaround that doesn't even work as well as you imply.

> Just use Windows. Install games from developers directly.

See how silly that sounds to you ?

Proton (a fork of Wine) can be used outside Steam. It's open source and hosted on github. There are also forks of Proton that are community maintained (e.g.: Glorious eggroll).

If you want to have the convenience of Steam, without Steam, you have projects like Lutris, which have community maintained scripts for each game. Those scripts are responsible for installing all the necessary dependencies and workarounds necessary for getting a game to work.

You can check https://www.protondb.com/ to see which games work well under Proton. If you don't want to use Proton, you can search the Wine application database for compatibility information: https://appdb.winehq.org/

I recommend Steam + Proton because it's the most frictionless way of getting games to work. The #1 complaint about Linux is how hard it is to do some things (like the guy I initially replied to), but it doesn't have to be that way.

I'm mostly buying games from GOG, not Steam. You can perfectly use Wine, Wine staging and Proton without Steam for them.

It's in the title of the post. You can run your VM in a regular window but at high performance (think gaming and professional stuff that's GPU heavy). You otherwise can't do this without a hardware KVM switch (or tossing the VM and just dual booting). Hardware KVM switches are expensive and often don't work very well. And still, with a KVM switch it wouldn't be running inside a window. It would consume your whole screen.

Is it possible to run Windows in KVM, without the extra GPU or KVM switch, but with degraded performance? Not for gaming, but for example for Office use?

yes you can, (Atleast if you can handle the extra CPU and Disk I/O). I think you should checkout winapps [1] which RDP's into the vm to give you a pretty seamless experiance.

P.S. Disk I/O can be a severe bottleneck on HDDs, so try this with a SSD.

[1]. https://github.com/Fmstrat/winapps

Yes, QXL can do that and has built-in support in e.g. virt-manager. It's not going to be fast, but it does work, and is how installation of Looking Glass can be bootstrapped without a physical monitor attached.

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