Minimal x86 Kernel Zig

(github.com)

109 points | by lopespm 11 hours ago ago

36 comments

  • WD-42 5 hours ago ago

    Here's one for Risc-V that's a little more fleshed out, also in Zig: https://github.com/Fingel/aeros-v/blob/main/src/kernel.zig

  • 6r17 6 hours ago ago

    I'm very surprised it's *that* short - handling one in rust i'm surprised by the very low amount of code to get that up. Thanks or sharing that was a first time reading some Zig for me !

    • pmarreck 5 hours ago ago

      what you’re experiencing is more or less why I am building some stuff in Zig instead of Rust

      • simonask an hour ago ago

        Looking at the code, I'm not really sure what part of this would be more verbose in Rust. This kernel does close to nothing, not even page table setup.

        Granted, the code writing to the VGA buffer will need to be in `unsafe` blocks, but yeah.

  • kunley 3 hours ago ago

    Why to spread confusion and call it bare metal when it's run under QEMU? Then it's not bare metal at all.

    In order to be run on bare metal it's needing another bootloader which the documentation only barely mentions.

    More on the naming: why to call it kernel?

    • cies 2 hours ago ago

      I agree, I'd not call this a kernel. It does not allow any software to be run on top of it. It just prints text to screen and halts.

      Even saying it "runs" on QEMU is a far stretch: it "halts", that's all it does. :)

      (it does run on hardware as per other commenters in this HN convo)

      • kunley 2 hours ago ago

        Ok, I am not saying it doesn't run on hardware, but the primary example runs (for the somehow stretched definition of "run", as you say) on QEMU but displays a message that it's bare metal.

        Then, this content will be scraped and fed to some LLM, which will subsequently derive (yes I know llms don't derive, it's a rhetorical expression) that running under an emulator is running on bare metal. Confusion for the masses! (Not to mention confusion for a reader already now)

        • cies an hour ago ago

          It does not "run" anything: it halts. :)

  • csense 8 hours ago ago

    Very neat. To clarify, Qemu can boot it, but I'm pretty sure you need some bootloader (e.g. Grub) to boot it on a physical system.

    • toast0 7 hours ago ago

      Looks like it's multiboot compliant, so you can pick your favorite multiboot loader. ipxe, grub, pretty sure there's some other ones out there.

      As it's multiboot, it should likely run on v86 too. It's always fun to have an in browser demo of a little OS like this.

    • anta40 7 hours ago ago

      If you want to use Grub, this tutorial works (see "Booting the kernel"):

      https://wiki.osdev.org/Zig_Bare_Bones

      Yes, just tried it.

    • flopsamjetsam 7 hours ago ago

      From the GitHub page:

      > It boots on an x86 (i386) machine via the Multiboot 1 protocol

      Yes, it does need a compliant bootloader on virtual or physical hardware.

  • boricj 2 hours ago ago

    I wrote something similar a while ago: https://github.com/boricj/hang-os

    It handles interrupts/traps and targets the aarch64 QEMU virt platform. It also features a HAL.

  • ajxs 9 hours ago ago
    • anta40 9 hours ago ago

      Both tutorials work fine on latest stable zig (0.15.2)

    • xx__yy 7 hours ago ago

      Thanks for sharing

  • drnick1 6 hours ago ago

    What's the point of doing this in "Zig" instead of C, the traditional choice for this kind of thing?

    • toast0 6 hours ago ago

      Because you can is a pretty traditional reason.

      Zig is supposed to be an improvement upon C, so doing C things with it seems reasonable.

      Kind of neat that there's no need for a separate assembly file although there is inline assembly. Might get better (or worse) syntax support for separate assembly files? But it doesn't make a big difference until there's more features that need it (interrupts, threads/processes and maintaining their stacks, syscalls, starting other processors, etc)

    • kunley 3 hours ago ago

      I guess one of good reasons is easy cross-compilation.

      But also, I can see some amount of weird hooray optimism in this project, like: totally confusing claim that the thing is bare metal when it's still being run under an emulator; also, calling it a kernel is a huge overstatement

    • flohofwoe 3 hours ago ago

      In this case, better tooling and consistency. E.g. the small block of inline assembly would already be trouble for some C compilers.

    • jandrewrogers 4 hours ago ago

      Zig is essentially a substantially improved and enhanced C, both in character and intent. There is a lot to recommend it for applications where you might otherwise use C.

    • mitchellh 6 hours ago ago

      Fun?

    • pmarreck 5 hours ago ago

      because Zig is simply a better C, often faster (normally at least as fast), but with way more safety guarantees or at least things preventing the vast majority of traditional C footguns from happening

      • bjourne 2 hours ago ago

        Zig is not faster than C.

    • 6r17 6 hours ago ago

      What's the point writing another kernel in C ???

    • moonlion_eth 4 hours ago ago

      because zig is lower level than c

  • aryalaadi 5 hours ago ago

    thats not a kernel

  • throwaway27448 7 hours ago ago

    Why choose intel? Let's build bootable software in 2026

    • xx__yy 7 hours ago ago

      I'm not that cluey, but from the README it sounds like it can be compiled for a bunch of arches

      • asQuirreL 2 hours ago ago

        It can be (cross-)compiled on whatever architectures the Zig compiler is available for, but the source contains inline x86 assembly, so you're not going to be able to build this for ARM or RISC-V.

  • messe 5 hours ago ago

    Minimal slop.

  • gethly 3 hours ago ago

    wtf? 10 lines of hello world code is not a kernel.

  • xx__yy 7 hours ago ago

    Gold! I see Zig, I upvote!

    • smallstepforman 24 minutes ago ago

      Well, in the real world we need at least polymorphism and operator overloading, but that is against the core Zig philosophy, so serious GameDev ignores it (which ironically one would think is the biggest core market for low level systems programming). Hence why new GameDev development still chooses C++, and Andrew’s project fails to gain a significant boost in users.