Raspberry Pi 4 OpenBSD based home computer/gaming console
A lot of existing software was video games. They were much simpler than those people play nowadays but they were still a lot of fun. Part of the fun was low latency.
I started working on a gaming console based on the raspberry pi that would have the kind of low latency that older home computers and gaming consoles had, and found a way to do that.
At some point, I realised that users would want to use a keyboard, read and write files, connect to the internet, stuff that is taken for granted with computers today.
So I wanted not to run on bare metal anymore, I needed an OS. Writing one from scratch would take me years and it probably would not be as good as an existing one.
But existing desktop operating systems tend not to be good for games, as they introduce latency and are able to stop a game at any time to do some other task, which can result in stuttering that the game developers cannot fully control or avoid.
I modified the OpenBSD kernel for the raspberry pi with gaming related extensions, in such a way that when the game runs there is no latency and no stuttering.
A game on my own fork of OpenBSD has the same performance of the bare metal code that I have written previously. And it can do file I/O, connect to the net and all that kind of stuff.
And when you quit the game it's just like normal OpenBSD so you can program it and make games yourself, browse the web and do all sort of stuff.
I am thinking that other people may want to have something like that, both for nostalgic reasons and for learning programming, so I thought of asking around and, if enough people like the idea, turn this into a product.
44 comments
[ 2.7 ms ] story [ 89.2 ms ] threadEven writing a game system for the raspberry pi zero w would be amazing.
The fact is that the zero does not have the computing power I want. The 3 does not have USB3 and that is a big issue for another reason.
It has to be the raspberry pi 4 :-)
I am only looking for people's opinions now
I miss that mojo of old simple games. Never thought latency on modern OSes could be a barrier.
For example, modern television sets have a "gaming" mode because in normal mode they somehow process the video frames to make them look better, in a way that introduces latency.
Someone who works on audio software told me that audio over bluetooth has a very high latency too.
There are several bits that can introduce latency in a system. The OS is the part that software developers can adjust and improve.
What does that even mean? What "gaming related extensions"?-- could you elaborate?
OpenBSD doesn't have any accelerated drivers for the GPU on the RPi, so I'm curious what your "no latency/no stuttering" modifications would even be, beyond perhaps maybe recompiling the kernel with HZ=1000 or something else..
That said yes, I would like to be able to turn this into a product.
There's a lot of logistics in selling this type of thing. Also the BSD license isn't exactly easy to sell something alongside of.
Have you considered open-sourcing and doing the ol' "if you like my work, buy me a coffee"
I know it's extremely communist of me, but I just can't imagine you not stepping on a lot of toes (both legally and otherwise) because of the spirit that OpenBSD was written in.
Why's that? There's no reason you cant have a closed-source commercial fork of BSD code. The Playstation 4 OS is a fork of FreeBSD: https://en.wikipedia.org/wiki/PlayStation_4_system_software
I thought that the BSD license was friendly to this kind of stuff.
If I step on people's toes I would ask for forgiveness and try to give them something back, which I think is just the right thing to do.
For example, I read that OpenBSD developers were sad that most of the contributions they got was from individuals more than from companies, when they actually help companies a lot.
Maybe this could be a way to change that situation?
At the end of the day I want to be happy with myself. I don't want to make enemies. Possibly, I would love to keep working on this for a living as I enjoy it more than everything else I did in the past.
This is not a product yet. If it's going to be, it's going to be a very long and hard way before that happens. Why is everyone so concerned about money at this stage?
Personally, I thought that this was a cool thing that some people would like. Maybe I could make a simple living out of it.
Most people comments seem to me like they are assuming that this is going to be a huge success that could make money and are worried that the other devs would be left out with nothing.
Isn't this a bit of a prejudice? And isn't it premature to assume it's going to be a success?
To me at this stage it's more about making a living out of something I love doing rather than becoming the next big tycoon.
I think the best model if you want to both share the code and make money is to offer commercial version with newest features, and open source a version that's a bit behind. As you publish a new version, you open-source the previous commercial version. This is more of a "source available" model because it actively discourages any community code contributions.
It is still not clear to me how to receive money as founder and maintainer on actual open source project, without resentments from contributors that don't get paid. Doesn't seem fair and has potential to turn into big drama.
Those are complicated matters.
I just have no idea how to do this properly at the moment. I am just hearing people's opinions for now and I'll try and do something that people are generally happy with. On the other hand, it's also true that one cannot please everyone.
To me it's like: "I have done something that I think is cool, let's see what people think about it".
I mentioned that I wanted to do a product out of this and people got emotional, as if it was granted that it's going to be a huge success.
I really wish it was that easy. I think that this is not realistic. It would take a lot of work from a lot of people who need to be paid because they need to pay their own bills to make this into a success. And it still could fail.
I regret having mentioned that I may want to turn this into a product, because it put too much focus on that rather than on the tech that I have developed.
I haven't written a driver for the pi graphics card or for HDMI audio. What I do with graphics is to save the existing state before beginning the game, do whatever I want during the game and restoring the state when it ends. With audio I am not doing it that cleanly as I believe that OpenBSD does not currently even touch HDMI audio registers.
As for the reduction of stuttering, when the game begins I stop 3 of the four cores, assign them entirely to the game ( also with new interrupt vector tables both in EL0 and EL1 ) and when the game exits give them back to OpenBSD. That way, while the game is running without interruption, the single core that is left to OpenBSD is free to run admin tasks. Since the game has a process that can be scheduled by that single core, the game can do networking or file I/O using OpenBSD, because the different cores have the same entries in the user space MMU tables and so they share memory and can talk to each other. OpenBSD cannot interrupt the game, it can only kill it if needed.
Regarding upstreaming my work the answer is "Probably not. But if the world wants it open sourced I am not against it and could think about doing a fork (Say we call it OpenBSD4Games). Or I could just give some help with the raspberry pi drivers."
The reason for that is that I am doing quite some stuff that am pretty sure the OpenBSD devs would not be happy to put in. OpenBSD is strongly focused on security. I am pretty sure they would not want to have some code in there that hijacks 3 cores out of 4 and gives them to a user process. Another example: I have been told that giving several contiguous memory pages to a user task is something that should not be done in OpenBSD. I understand why but then I give a game quite a few contiguous memory pages that the hardware will use for the frame buffer and so has to be contiguous.
Also, this is prototype code. It works for me, it still needs a ton of work and might not even be 100% correct. I cannot possibly understand all of the little details in the kernel in 2 months.
I am proud of this achievement though and would love to be able to turn this into a real product that many people enjoy.
Regarding the "home computer" part, I thought about game devs. When doing a game, it's not only the game code that is important. The tools are very important as well. So I built GNUstep ( on OpenBSD it does not currently work on arm64 ) so that it's super easy to build tools for game development in Objective-C.
Also I thought about playing around and experimenting, and I am planning a GUI app with GNUstep that integrates a C/C++ interpreter called cling, which is developed by CERN for their physics simulations if I am not wrong. With that, a game developer will be able to experiment with code and tweak it in a way that is similar to what Xcode playgrounds does with swift on the Mac.
https://youtu.be/KhRnGbVhejk
Could you share any resources you used to understand, navigate, and extend the OpenBSD kernel?
There doesn't seem to be much in the way of resources available on that -- nothing like the NetBSD Internals guide, not to mention the wealth of information on the Linux kernel.
A blog post on that would probably be widely appreciated as well, if you have the time :)
The article that got me started is the pdf taken from a conference called "OpenBSD Kernel Internals: The Hitchhiker's Guide" mentioned here: https://www.openbsd.org/events.html
I just checked the link and the site seems to be down for me now, so I refer you to that page. Hopefully it will come back up or the link will be updated.
In that article it describes how to add a syscall to openbsd. So you start by writing a very simple one just to see that it works and get comfortable rebuilding the kernel and testing your syscall with a userspace program.
Then, since I roughly knew what I wanted to achieve, I started looking at kernel code and finding the parts relevant to what I wanted to do.
Then take baby steps with your changes, try and fail until you succeed with a small bit before moving on to the next. Especially value failures, as they give you hints about what is going on. Think why it could have failed and try a different approach that should not fail in the same way. Very tedious and time consuming, but a very good way to learn when you don't have the books.
Then looked for hints on the web and talked to the awesome people on the mailing lists and on the reddit OpenBSD channel.
I did not talk too much to people though, I asked a few questions at the beginning and then had a short conversation about allocating contiguous physical memory to a userspace task, which is something that OpenBSD does not do. I figured out how to do that by myself, by trial and error. Same with other details.
My mindset was: I know how to do this with bare metal, there must be a way to connect to the kernel code and do the same in a way that does not break things too much if I keep it limited in scope.
I hope this helps :-)
> I am thinking that other people may want to have something like that, both for nostalgic reasons and for learning programming, so I thought of asking around and, if enough people like the idea, turn this into a product.
Is a HN post the place for this?
[1] https://raspberrypi4gameconsole.blogspot.com/
[2] https://news.ycombinator.com/item?id=26544635
If the admins feel like that, please remove the offending post(s). Or ask me to amend them.
I have made something that I think is cool and with the hope that others liked it, but if it's out of place I can only apologise.
Cool project!
I am nostalgic of Commodore64 too.
The thing that made many of us go down the rabbit hole was the immediacy of the interpreter, begging you to enter some commands 2 seconds after turning on your computer.
The perceived small gap between the commands you enter in a programming language and the games you could play with the machine contributed largely to the curiosity and willing to learn more.
On a modern computer, building the right interpreter is challenging. There is a trade-off between the simplicity of the language and what you can achieve with it. You won't impress today's kids if it allows you to only print text on a scrolling page.
But I think one can build something really great. There could be an integrated sprite editor (with a graphic UI) and the interpreter can use them right away with something like: Sprite1.visible Sprite1.x = 10
emphasising again the immediacy. Those "sprites" could be 3d objects as well.
[0]: https://www.lexaloffle.com/pico-8.php?page=faq
[1]: https://github.com/ftsf/nico
https://freds72.itch.io/poom
And it illustrates perfectly why what I am doing is cool.
I played that game in the browser and it looks great. But the controls are quite a bit laggy. That is not the developer's fault, they cannot do much about it. The medium that they chose is not designed for low latency.
My project enables developers to make a game like that more fun when you actually play it.
Low latency is great, but not a reason to pay more than MSRP. You’ll need to show me why it makes a difference and why it is worth paying the extra money. Also, I already have a Raspberry Pi 4 - can your “product” be added on to the one I already have?
First of all, consider that I am just a guy who usually programs for a living and has been in a personal situation where he could not work. For some time I had an idea in my mind about this stuff and instead of getting depressed about not being able to work I went for it and started making it.
I am not asking for money at present, I am only asking for opinions.
My "product" is not a product yet, it's a prototype, there is no cost at the moment.
I clearly said in another reply that I am not even against open sourcing it, if that is what has to happen. Or maybe people will not be interested enough and forget about it. Who knows.
What I am saying is that I have spent quite some time working on this stuff and at the end of the day I have to pay my bills too, so it would be nice if I could make some people happy and get something back.
What worries me is that I genuinely believe that this is an interesting approach to "an operating system for games and game development" and I may not be able to sustain its development for much longer.
In its current form it can be added to a raspberry pi 4, yes, as this is what I have done myself.
Now for the question about why would you be interested. If low latency gaming is not interesting to you, then it would not be the product for you.
You are right, there is lots of great software out there that can be obtained at no cost.
That is true for everything. For example I don't watch much television so I don't use paid tv services.
That was meant to be constructive :)
I enjoy typing and drawing on my iPad Pro, and one of the reasons it is enjoyable is that the iPad Pro has very low input latency.
The "low latency" thing is a bullet point on a spec sheet. What sells me is the enjoyable experience.
Your interesting approach is not what people are going to buy. They're going to buy what happens because of it. That's what you've got to sell if you want to sustain the development!
Uh, ok, sorry :-) It's just that I have been a bit upset by some other comments that made me feel like I am a bad guy only because I did something different and said it would be nice to make some money out of it.
> I enjoy typing and drawing on my iPad Pro, and one of the reasons it is enjoyable is that the iPad Pro has very low input latency.
You would be surprised. Apple has put a tremendous amount of effort to make their stylus low latency, and they did a terrific job. The latency is good for handwriting and drawing, or for typing. But for games I believe that there is still a very long way to go. Early machines had a solution that worked very well but the industry evolved in a completely different direction.
> Your interesting approach is not what people are going to buy. They're going to buy what happens because of it. That's what you've got to sell if you want to sustain the development!
You're absolutely right about this. I am painfully aware of this. I have many years of "interesting approaches" that go nowhere for lack of ability to connect with people on that level.
You know, different people have different abilities. There are exceptional people who are good both at their craft and at selling it, some only at their craft. Picasso and Van Gogh, Edison and Tesla, Gauss and Galois.
I am hoping to connect with other people, with experience in the area of selling and communications.
But more practically, there are a few places to get started. One I am looking at is the retro gaming space. Input latency is a big deal there. If I can manage to give people a low latency retro console, they are going to be interested. I have to customise an existing emulator, which I will be looking into after this round of "marketing", i.e. posting about my project on social media.