Writing a RISC-V OS in Rust: System Calls

Like WebDAV.

As far as I can remember Inferno did syscalls in a different way, given that Limbo with DisVM was the main programming language.

> Use an rpc protocol to do all the talking to objects within the system which are exposed as files.

At some point, you're just adding pointless layers of indirection by doing this. NT tried this approach, and it is anything but "simple".

You can do many things quite naturally by interacting with bytestream-like or block-like objects that are exposed via some sort of hierarchical namespace ("files"), but this doesn't really cover everything. Some things may be better done, even in a script, by interacting with a "binary" that in turn just wraps a binary library exposing some kind of ABI.

I'm a n00b when it comes to these sort of things, how would one upload a texture to a GPU, for example, using this? Open the "GPU driver file", seek to some specific location and write the texture bytes?

Stuff like "this board/chip needs real time response in order to not melt itself despite not being able to trust that the OS is hard real time" like System Management Mode was originally intended.

It's also been handy for trying out supervisor mode concepts and adding software based support on chips that don't support all the features like hypervisor extensions.

Machine mode is the equivalent of el3 on arm. That's where processor firmware tends to run. There is no paging and very little in the way of security boundaries or seatbelts.

It was supposed to be where vendors can patch up differences and provide platform bindings. The (standard) Linux kernel expects to be started in S mode and doesn’t include M mode code. OpenSBI is an example of template firmware that belongs in M mode, not OSes.

I suspect that whatever replaces Linux will probably involve a paradigm shift at the lowest level. Perhaps capability-based IPC, perhaps seamlessly integrating local and networked nodes, etc. It’s going to take major major improvements to move the world off of the Linux kernel.

I agree: Trying to create a new general-purpose OS is futile. You're handicapping yourself by attempting a feat which likely can't achieve anything beyond your own satisfaction, which will be limited by the aforementioned self-handicapping. It's like sublimating your musical drive in a knock-off, unoriginal rock band in the vague hope you'll someday become the next Nickleback. Go for the gusto and put the Research in Research OS. Make something to explore an idea mainstream OSes can't pursue because it would break too much compatibility. Be Captain Beefheart, or at least Tool.

Fuchsia has the advantage that Google can force it onto a bunch of phones, Chromebooks, and personal assistants and get instant "market share".

I think it's likely the #1 threat to the Linux dominance in the backend, ironically by hijacking the front end first. Based on market share, it could create an expectation that AWS, Azure, etc, provide backend support. Doesn't hurt that Google owns K8S as well. See, for example, EKS. Google can manipulate Amazon in select spaces.

Only with the deep pockets of FAANG like companies.

Android or ChromeOS would never have taken off the ground without Google's keeping pushing them forward no matter what. In both OSes the kernel is hardly exposed to userspace, Google could move to something else and it would be hardly noticeable to app developers (OEMs and rooted phones is another matter).

And then there is Fuschia.

Outside general-purpose domain, the IoT world is getting full of BSD licensed OSes, RTOS, Zephyr, NuttX, Tizen RT.

Ironically Zephyr is managed by Linux Foundation, although it doesn't have anything to do with Linux code.

That would be wrong battle to fight first. Pick one special-purpose market it can win and take that. Rinse, repeat.

Dog knows IoT needs something a lot better than Linux to run on; fat flabby old-school hacker-culture footguns are absolutely not an option when smart tech is being built into everything and everyone. That tech must be small, hard, absolutely focused, and take ZERO shit from NO-ONE; starting with itself.

Remember, the only code which can be 100% guaranteed impossible to compromise is code that isn’t there. Today’s Linux kernel is around 20 MILLION LOC, and counting. No prizes for figuring what any competing product’s USP must be.

..

“General-purposeness” designed into the product at the start enables it to adapt to each new market quicker and easier, but it shouldn’t be a public selling point in itself. Because the moment you start pitching it as being “everything to everyone”, everyone wants to throw their own crap into it as well—and you’re back to building ”another Linux”, in a market that already has a resident Linux and no room or need for another. Think smart. Don’t covet all the things that Linux does well and try to replicate those. Instead, identify the things Linux doesn’t do well (and CAN’T ever do well because of why and how it’s built) and knock those balls clean out of the park.

Think about how Steve Jobs finally beat Microsoft at its own game. Not by building a better PC, but by fundamentally redefining what “Personal Computing” means; and then being first to market with the perfect product for that.