liblinux VS steam-runtime

> libc isn't really getting in the way here.

For the standard set of system calls, the libc is pretty great. For Linux-specific features, it could take years for glibc to gain support. Perhaps it's gotten better since then, perhaps it still takes years. I don't know.

Years ago I read about the tale of the getrandom system call and the quest to get glibc to support it:

https://lwn.net/Articles/711013/

A kernel hacker wrote in an email:

> maybe the kernel developers should support a libinux.a library that would allow us to bypass glibc when they are being non-helpful

That made a lot of sense to me. I took that concept and kind of ran with it. Started a liblinux project, essentially a libc with nothing but the thinnest possible system call wrappers. Researched quite a bit about glibc's attitude towards Linux to justify it:

https://github.com/matheusmoreira/liblinux#why

Eventually I discovered Linux was already doing the same thing with their own nolibc.h file which they were already using in their own tools. It was a single file back then, by now it's become a sprawling directory full of code:

https://github.com/torvalds/linux/tree/master/tools/include/...

Even asked Greg Kroah-Hartman on reddit about it once:

https://old.reddit.com/r/linux/comments/fx5e4v/im_greg_kroah...

Since the kernel was developing their own awesome headers, I decided to drop liblinux and start lone instead. :)

It gives you access to 100% of Linux's system calls. It eliminates a lot of global state. It gets rid of a lot of legacy libc crap.

Years ago I wrote a fairly referenced rationale in my liblinux project:

https://github.com/matheusmoreira/liblinux/blob/master/READM...

> Now, do I think it would make total sense for syscall wrappers and NSS to be split into their own libs (or dbus interfaces maybe) with stable ABIs to enable other libc's, absolutely!

I worked on this a few years ago: liblinux.

https://github.com/matheusmoreira/liblinux

I'm not developing it anymore though because I found out the Linux kernel itself has a superior nolibc library:

https://github.com/torvalds/linux/tree/master/tools/include/...

It used to be a single header but it looks like they've recently organized it into a proper project!

I wonder if it will become some kind of official kernel library at some point. I asked Greg Kroah-Hartman about this and he mentioned there was once a klibc:

https://old.reddit.com/r/linux/comments/fx5e4v/im_greg_kroah...

> This is something the BSD's got absolutely right.

BSDs, every other operating system really, force us to use the bundled C libraries and the C ABI. I think Linux's approach is better. It has a language-agnostic system call binary interface: it's just a simple calling convention and the system call instruction.

The right place for system call support is the compiler. We should have system_call keywords that cause it to emit code in the aforementioned calling convention. With this single keyword, it's possible to do program literally anything on Linux. Wrappers for every specific system call should be part of every language's standard library with language-specific types and semantics.

I'm not using this stuff professionally, it's just my own home lab's virtual machines with little services implemented as freestanding C programs. Not doing anything fancy right now, much of it was just to see if I could do it.

I've seen other people commenting here on HN saying they're using the same approach so it's defenitely not my invention.

I published some of my work in the form of a liblinux that I use to make system calls:

https://github.com/matheusmoreira/liblinux

I'm not developing it anymore though because I found out the kernel itself has a nolibc library:

https://github.com/torvalds/linux/tree/master/tools/include/...

It used to be a single header but it looks like they've organized it into a proper project.

That's awesome. I didn't know about rwildcard until now. Is it part of GMSL? I searched for rwildcard on gmsl.sourceforge.io but didn't find it.

I think my function is needlessly complicated compared to rwildcard. Here's my code:

https://github.com/matheusmoreira/liblinux/blob/modular-buil...

https://github.com/matheusmoreira/liblinux/blob/modular-buil...

The file? and directory? functions were inspired by GMSL.

I wrote a general recursion function. It takes a function to apply to lists and a function to compute whether an element is a base case.

The recursive file system traversal function applies a directory globbing function to the list of paths and has file? as base case.

The find function filters out any items not matching a given predicate function. It was my intention to provide predicates like C_file? and header_file? but I stopped developing that project before that happened.

I think rwildcard is probably simpler and more efficient!

> It turns out that unless the game is explicitly marked (by Valve reviewers), Steam Deck will use the Windows build + Proton even if a Linux version is available.

I found this which sounds like it's not the default, but is in fact a result of compatibility testing:

> If your game has gone through Steam Deck compatibility testing and the testers reported that the native Linux version didn't work (because of #579), then it might have been flagged to run the Windows binaries via Proton by default, instead of the native Linux version.

per https://github.com/ValveSoftware/steam-runtime/issues/585

> Where is it written that steam-run will magically execute most binaries without patching them?

Somewhere in here: https://github.com/ValveSoftware/steam-runtime

:p

But I do get what you're saying. Once Flakes are default, I hope people start a proper push to clear up documentation and streamline the development process. The end-result is amazing, and the perfect OS/packaging system for my needs. The means of getting there... need a lot of work. I'm along for the ride either way.

I think they have something a bit like a container built into Steam: https://github.com/ValveSoftware/steam-runtime

this is for steamworks API, my understanding is there's a separate SDK for consuming Linux dependencies like glibc. Like Soldier runtime, Sniper runtime, and so on. Am I wrong in thinking these are two separate SDKs? here's the link to the other SDK I'm talking about: https://github.com/ValveSoftware/steam-runtime

I'm not sure we can distribute a flatpak or an appimage through Steam. They have their own controlled environment called Steam Runtime (https://github.com/ValveSoftware/steam-runtime) in which I should compile to be sure it runs everywhere (very similar to what I am doing). Last time, I look at this, it wasn't very clear and they supported only old versions of GCC. But it seems the documentation improved and now that I succeeded in building a modern version of GCC in my own container, maybe I could do that in theirs.

I believe it's usable outside of Steam: https://github.com/ValveSoftware/steam-runtime though the instructions are not particularly clear. There's also a link to the APT repo they use as a reference: https://repo.steampowered.com/steamrt/

Looking at the Flatpak version, if you want to use Proton versions 5.13 or newer with Steam in Flatpak, you need to install Flatpak from backports https://github.com/ValveSoftware/steam-runtime/issues/294 . Using Flatpak saves having to install i386 if that matters to you.

> Game developers would be fine to target a single distro like Ubuntu 22.04.

Valve has its own container-only Linux distribution, called "Soldier Runtime" (https://github.com/ValveSoftware/steam-runtime); especially for games distributed on Steam, it probably makes more sense to target that distribution instead of Ubuntu.