An interview with the developer of DXVK, part of what makes Valve's Steam Play tick

What started as a large article talking to developers about Steam Play required splitting off before it became too big. For now, I give you a chat with the developer of DXVK, Philip Rebohle.

For those that aren't quite up to speed, DXVK is a project that provides a Vulkan-based D3D11 and D3D10 implementation for Wine. It's part of what makes Valve's Steam Play "Proton" work. In simple terms, games built to run on Windows via DirectX can be run with DXVK/Proton, so that they can be played on Linux.

I believe that DXVK and Steam Play are some of the most interesting projects to come out in the last few years, which could possibly help push Linux gaming forward. You can see more of my own thoughts in the previous article. I don't want to ramble on too much about what's already said, so here it is below.

GOL: Firstly, as the developer of DXVK, how did you get started with Vulkan and DirectX?

DXVK: “I've always had an interest in graphics programming and used OpenGL in the past for some hobby projects that never really evolved into anything useful, and started experimenting with Vulkan once it came out.

My first contact with D3D11 was actually when I tried to debug a rendering issue with a D3D11 game on wined3d, but since most of its concepts are very similar to what we have in OpenGL and Vulkan, it wasn't too hard to figure out. Except of course for the parts where Microsoft's documentation is terrible, and there are a lot of those... sorry, I just had to rant about that.”

GOL: What gave you the idea for DXVK? Why did you decide to make it?

DXVK: “It's a combination of being dissatisfied with the performance of wine's own D3D11 implementation, not wanting to dual-boot to Windows anymore, and being inspired by the VK9 project which I had been keeping an eye on for some time. And I really wanted to get one specific game to work.”

GOL: Since you're now contracted by Valve, how did that happen? Must have been quite a shock initially to have Valve approach you?

DXVK: “It wasn't all that spectacular - they contacted me when News made the round that DXVK could run Nier [NieR:Automata] back in late January, and when offered to work full-time on the project after a friendly chat, I couldn't really refuse.

There are a lot of things that probably would not have happened if Valve hadn't been backing the project - such as driver developers fixing their Vulkan drivers for DXVK or reporting bugs, or Vulkan getting a transform feedback extension.”

GOL: Do Valve give you much input in the direction of DXVK or do you continue to work on it freely, simply with the backing of Valve to allow you extra time on it?

DXVK: "There are some things that I probably wouldn't have done without them requesting it, such as adding OpenVR support or focusing on certain games early on, or trying to squeeze more performance out of specific workloads. But I spent most of the time just improving overall game compatibility and performance."

GOL: There have been a lot of people asking about anti-cheat, things like Easy Anti-Cheat, BattlEye and so on where the games won't run in Steam Play/Wine. People seem confused where the problem really is. Is it something Wine needs to solve to support them?

DXVK: "I'm certainly not an expert on anti-cheat or DRM technology, but those that don't work are typically very invasive, access Windows kernel APIs, rely on undocumented APIs, and may prevent debugging. All of that makes it very hard for Wine to support them."

GOL: How has the reception been to DXVK? Has it changed since Steam Play?

DXVK: “Depends on who you ask. People who just wanted to play their games on Linux were generally excited when DXVK started running more and more of their games, part of the wine community isn't exactly happy about it being a separate project, and there are of course those who dislike wine in general, but more on that later.

Has it changed since Steam Play? I don't think so. Things just have calmed down over time. Many of those using Proton now have been using Wine, Lutris, DXVK etc. before, and new users seem to be happy with Proton as a whole, which DXVK is a part of.”

GOL: Any hopes for the future for DXVK? How do you feel about developers concerns with it possibly causing less native Linux ports?

DXVK: “It should hopefully fulfil its purpose and make users who currently dual-boot or run some crazy VM setup for gaming switch to Linux as their primary gaming platform, and maybe attract a few new users altogether.

I genuinely don't know if it'll reduce the number of native ports. Maybe it will, maybe we'll get more ports due to a higher market share, maybe some studios will adopt Vulkan for better compatibility with Proton - anything can happen. And while I'd take a good port over wine any day of the week, there's one thing that everyone seems to forget in this discussion: It increases the number of playable games on our platform, and that just can't be a bad thing.”

Thanks again for having a chat! It's always great to get some background on such important projects like this. I have to agree with Rebohle's ending remark there too, having more games be compatible on Linux is going to be good for us in the long run.

We should have more articles up from other developers in future. Depending on responses this may come in one big feature or a few smaller articles over the next few weeks. We're casting a wide net, so if you're a developer of a game, a game engine, a game porter or anything of the sorts and want to have a chat about Steam Play, do get in touch!