Show HN: My from-scratch OS kernel that runs DOOM

(github.com)

226 points | by UnmappedStack 12 hours ago ago

50 comments

  • donnachangstein 9 hours ago

    A few months work by one guy and already more capable than the Hurd.

    Imagine what you could accomplish given 35 years.

    • dxroshan 7 hours ago

      > A few months work by one guy and already more capable than the Hurd

      It is no way capable than Hurd. It is a cool project though. Have you used Hurd recently? It can run a modern desktop.

      • donnachangstein 7 hours ago

        I searched YouTube for actual evidence of Hurd booting to a desktop and only found two videos of Hurd freezing during boot, and a third video of RMS explaining to a very confused convention attendee that he's "never installed GNU slash lynn-ox" because he could just ask someone else to do it.

        No videos of Hurd running Doom either, but anyone is welcome to create one and share.

        • dxroshan 5 hours ago

          The programming interface that Hurd provide is similar to that of any modern operating system. So, it can run pretty much any program that runs on Linux or BSD, but you have to port it. Doom is no exception. If you cannot find a video of Doom running on Hurd on YouTube, it doesn't mean that Hurd can't run Doom.

          Hurd is sure not a successful project, but it is a capable operating system. Linux comes with a lot of device drivers for all sorts of hardware, so Linux nowadays can run almost everywhere. But that is not the case with Hurd because only a small number of people are contributing to this project and it is largely eclipsed by success of Linux. But it is an extensible system so if you want support for a hardware, you can develop a driver for it. But nobody is interested.

          If you haven't seen Hurd running a desktop, I will introduce you to Debian Hurd (https://www.reddit.com/r/linuxmasterrace/comments/18i6e94/de...). It is a Debian distribution with Hurd as the kernel instead of Linux. It comes with Xorg and you can install XFCE, OpenBox. Basically, you can install any desktop that render on CPU. Desktops like GNOME and KDE need more infrastructure. They relay on modern GPUs and uses direct rendering. In Linux, we have DRI and Mesa for this. As of now, Hurd doesn't have any such infrastructure. As I have already said before, a lot of people are contributing to Linux and only a handful of people are contributing to Hurd.

          • k__ 3 hours ago

            If it can run nginx and node.js on a VPS it could be a nice alternative to Linux.

            • shakna 3 hours ago

              The current Debian/Hurd port of nginx is outdated, but runs fine.

              There's been a few problems with nodejs, as libfuse compatibility isn't the latest yet. Some libraries work fine. Some explode. So you'll have to compile it yourself.

              Python and Go, however, should run out of the box just fine.

        • blendergeek 44 minutes ago

          Its been a few years but I ran HURD in a VM and it ran a nice X Windowing system. Its been a few years though so I don't know what HURD is capable of today

        • gertop 6 hours ago

          Hurd is for sure a failed project and it can't realistically run a modern desktop as claimed, but it's more capable than you give it credit for. For example, see:

          https://www.debian.org/ports/hurd/

    • fr4nkr 4 hours ago

      Hurd isn't exactly a useful project, but using Doom as the benchmark for the capability of an OS is a bit ridiculous.

    • UnmappedStack 9 hours ago

      Haha not quite at the point Hurd has gotten. I'd be very happy if I could last that long on one project though, I have a tendency to get bored after a few months sadly.

      • parl_match 8 hours ago

        > Haha not quite at the point Hurd has gotten

        that's true, you've only shipped to one computer, while they've shipped to dozens!

  • the_hoffa 6 hours ago

    Ok, but can your tacos run DOOM??

    I kid I kid ;) That's a commendable effort and nice job! Question though: was it an effort to make TacOS using DOOM as a "standard" or was it an effort to make an OS dedicated to running DOOM run from scratch?

    And I don't ask from any place but actual curiosity. I made an absolute bare-bones-cant-do-anything-but-boot type OS way back "in the day" (like almost 30 years ago, ack!!!) just for my own education/fun, but the idea of having a dedicated OS that can basically only run DOOM, yet be ported to anything would just make the "can it run DOOM" meme so much more ironic and fun!

    Nice stuff! Keep it up!!

    • UnmappedStack 5 hours ago

      Well, it can do a little more than run Doom, that's just the latest milestone as to what was ported last. It wasn't a huge effort, maybe took a week or so to get Doom itself running including adding libc requirements for Doom, but what came before that was a fair bit more groundwork. I used DoomGeneric, which is basically a fork of Doom which is made to be very portable. I hope I answered your question, I might have misunderstood.

  • planck_tonne 11 hours ago

    Hi, congratulations! You must be feeling proud. Nice choice of proof of concept (DOOM).

    Sorry to disappoint you but all I have are some noob questions.

    What would be the steps to run this on a laptop? I take it that after building it there would be a process similar to, say, setting up dual-boot in a Windows PC? (Whoa I'm asking a stranger on the Internet how to run dangerous software on my computer...)

    If one wanted to undertake such a project, do you have any recommendations of textbooks or other reading material? I had some OS & related courses in university (I'm EE, so computer-adjacent), but they were all very abstract / high level / conceptually-focused. I'd love something more concrete. It doesn't have to be x64.

    • khaledh 26 minutes ago

      I wrote a kernel as well (not complete yet), and I documented all the steps I'm taking. A lot of people found it useful: https://0xc0ffee.netlify.app/osdev

    • lolinder 8 hours ago

      Meta comment, but I'm pretty disappointed that this got downvoted so much. You're asking some good questions that prompted useful answers and showed sincere interest in someone's work. Don't get discouraged by the downvotes, keep learning!

      • owebmaster 8 hours ago

        Not being upvoted to the top doesn't mean downvoted. Your negativity is baseless.

        • lolinder 7 hours ago

          The funny thing about meta comments is that they can change the status quo that they're commenting on (that is, in fact, part of their purpose), and once they've made the change they seem pointless to those who come later.

          At the time of commenting this comment was totally grayed out at the bottom. That's a pretty dour welcome for a new user to a community that's ostensibly interested in anything that gratifies curiosity.

          • defrost 7 hours ago

            Completely fair point.

            I've vouched several green user comments in the past six hours that had been flagged and gone to dead for no apparent reason, the GP comment you spoke for was one that others had kicked to dead ( usually I'm flagging obvious spam comments straight to dead ).

    • UnmappedStack 10 hours ago

      Not disappointed at all to answer! Running it on my laptop was literally just formatting a USB with the ISO and booting from the USB.

      I would recommend checking out https://osdev.wiki to start out if you want to write a kernel, as well as reading relevant specifications (such as Intel Developer Manual and the specs for any drivers you write). I don't really know much about non-x86 kernel dev but most of the concepts are the same as far as I know, just different technical implementations. There's a link to a discord server on the project's readme, there are some very smart people in there who I'm sure would be more than happy to help you out.

  • tamat 3 hours ago

    Great work, I would love to have the skills to do something like this, but I can see you had to read lots of specifications to achieve this and thats my weakest point.

    One silly question you may know: Imagine you wanted to use GPU acceleration, even in the smallest form. How hard would it be to build a driver for the GPU? Do you think there is good documentation about it?

    • UnmappedStack 3 hours ago

      Umm that's probably the extreme end of OSDev which I likely wouldn't be able to do, at least not for a driver you can buy. Qemu's emulated GPU is documented decently and could be possible, but things like nvidia GPUs are badly documented (and until recently, the docs were fully closed source) - even Linux has issues with this (and I actually see a few other hobby OS devs who just use Linux's GPU drivers in the end). There aren't a lot of things I've marked as near impossible but writing a genuinely decent GPU driver for a common GPU isn't really something I imagine I'll ever be able to do sadly.

      • noone_youknow 33 minutes ago

        The docs for intel’s integrated offerings seem pretty good, I’m planning to do a driver for those on my toy OS. Anything else is hit and miss in terms of availability of information unfortunately.

      • tamat an hour ago

        thanks for your response. Thats what I heard but I was wishing things to change...

        I was also thinking about integrated GPUs like the one in a RPi or other SoCs

  • finalhacker 2 hours ago

    Cool! Does OS kernel related to CPU model? Can I boot this kernel in KVM?

  • kuberwastaken 2 hours ago

    THIS IS AWESOME Love the project too!

  • badmonster 6 hours ago

    Very cool project! How are you handling process isolation and scheduling in TacOS?

    • UnmappedStack 6 hours ago

      I use paging for virtual memory, which gives each process it's own address space. I have a round-robin scheduler connected to the PIT driver, so every 10ms the PIT fires an interrupt which triggers the scheduler, which selects the next task, saves the current state of the previous task, switches to the new address space, switches the stack, restores registers of the task, then uses the iretq instruction to switch to ring 3 user mode and jump to the instruction pointer.

  • waschl 7 hours ago

    Welcome to the club! Did almost the same and really enjoyed the serenity of doing something which never will end up in a product

    https://jakobbr.eu/2024/08/19/writing-my-own-x86_64-operatin...

  • torcete 2 hours ago

    Wow congrats, this is very impressive.

  • andrewmcwatters 8 hours ago

    From-scratch kernel straight to DOOM is some top-tier hacker cred stuff. You must be very happy with it running on real hardware. Very cool.

    • UnmappedStack 4 hours ago

      Yes, quite happy with real hardware. The kernel isn't exactly straight to Doom, it boots into a shell which you can just run Doom from, but yeah lol.

  • thewileyone 10 hours ago

    Dude, I'm impressed cause I don't the energy to build my own OS kernel!

    But here's a wacky idea. Just set it up so that the OS only runs DOOM as default. Boots directly into Qemu and runs DOOM, nothing to select or change. Maybe something you could fold other games into so that they can run off a USB boot loader. Might be appealing to people who don't want to install or compromise their base setup.

    • UnmappedStack 10 hours ago

      I could probably do that. The init program, which is a userspace program called by the kernel which spawns everything else, currently enters the shell but it'd be quite simple to make it just boot into Doom immediately. It's still not quite stable enough for actual usage, but it is able to boot off a USB at the moment, yes.

  • pkoird 11 hours ago

    Really really love the name.

    • aoki 10 hours ago

      In the fine tradition of Nachos and Pintos! (Still waiting on Burritos - which would obviously have to be based on functional programming principles - and Churros.)

      • khazhoux 9 hours ago

        Burritos are just monoids in the category of endotacos.

        • Octoth0rpe 9 hours ago

          welp I think I found my favorite comment ever.

  • halfer53 5 hours ago

    Nice work!!!

  • gitroom 11 hours ago

    Dude, getting Doom to run on your own kernel is epic - I gotta try building some wild stuff like this someday

    • UnmappedStack 11 hours ago

      Yeah definitely an achievement I'm happy with. I've got a bit of refactoring to do, ANSI parsing etc then I'd like to port more - perhaps even Vim (or another portable Vim-like editor called Dim)

      • edoceo 10 hours ago

        Could you explain more about why you'd need to port things? If you have a libc, shouldn't it "just work"? Do you have to scatter #define or #ifdef all over? What about if you wanted to support Golang? Would you have to implement a bunch of syscall?

        • UnmappedStack 10 hours ago

          Well, the LibC is still quite small, and the syscalls aren't really compatible with Linux. A lot of things to port, for example Vim, require system libraries such as ncurses which need syscalls that aren't in the LibC. I don't really need many #ifdefs, at least not for most things, as it's a more or less posix-based libc.

  • KerbalNo15 11 hours ago

    This is so cool