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tombert 22 hours ago [-]
I've thought about doing something like this but I am only very recently getting into low-level OS stuff.
I can't remember who said this, but they called "Erlang an operating system for your code", and I think that's fairly accurate. When I build an Erlang app, I don't build it the same way as I would with Rust; I have a lot of independent gen_servers that do operate independent from each other.
The Erlang VM is (roughly) preemptive multitasking, and even each process has its own GC, so it does feel like it could be a natural fit for its own operating system without having to live on top of Linux.
calvinmorrison 22 hours ago [-]
There's some definite prior art here where they worked on that a LOT.
You know, I read those slides when they were new, and I apparently just completely forgot about it.
Not that it's not interesting, just that my brain is dumb sometimes.
toast0 21 hours ago [-]
Unfortunately, the hydros project website is gone. I'm not sure if it moved somewhere.
kajogo 43 minutes ago [-]
super interesting!
mixedbit 23 hours ago [-]
Is the OS implemented from scratch, or is it a stripped down version of some existing OS?
toast0 23 hours ago [-]
The kernel is pretty much from scratch. It provides a FreeBSD compatible syscall interface for the syscalls that BEAM calls, as well as the FreeBSD runtime loader. I do make healthy use of FreeBSD libraries to provide the OS, you can get an idea of what I pull from the file names in the Makefile [1]. Building an OS is a lot, so I tried to stick to the parts I find fun and interesting. Things like a NIC driver in Erlang [2] (with NIFs to copy to/from device memory). But process / thread creation is original, memory management is original (not necessarily good), time keeping is original, etc. I used existing code and interfaces so I didn't have to write a bootloader, memcpy, and lots of other stuff.
DragonFlyBSD would be really interesting here as well since its kernel has Light Weight Kernel Threads that use message passing. Similar in shape to Erlang/BEAM. Though I guess you've built the kernel in Erlang... so wrong abstraction.
toast0 19 hours ago [-]
My kernel is in C. BEAM is in userspace. Most of the drivers are in userspace too. Turns out, if you let userspace mmap whatever address it wants to, and have access to all the i/o ports, plus have a way to hook interrupts, you can write drivers in userspace.
You could run beam as init with an existing kernel, but I wanted to explore something with less kernel.
lightandlight 21 hours ago [-]
> browser-based demo
Wait, so is the browser running a JavaScript build of Qemu? /
toast0 21 hours ago [-]
I don't think v86 [1] is based on qemu, but it's a javascript (well javascript + rust->wasm) virtual PC. Not my project, it's super lovely for hobby os demos though. (And they've taken a couple of my PRs!)
I can't remember who said this, but they called "Erlang an operating system for your code", and I think that's fairly accurate. When I build an Erlang app, I don't build it the same way as I would with Rust; I have a lot of independent gen_servers that do operate independent from each other.
The Erlang VM is (roughly) preemptive multitasking, and even each process has its own GC, so it does feel like it could be a natural fit for its own operating system without having to live on top of Linux.
https://www.erlang-factory.com/static/upload/media/149858389...
Not that it's not interesting, just that my brain is dumb sometimes.
[1] https://github.com/russor/crazierl/blob/main/Makefile#L23
[2] https://github.com/russor/crazierl/blob/main/src/rtl_8168.er...
You could run beam as init with an existing kernel, but I wanted to explore something with less kernel.
Wait, so is the browser running a JavaScript build of Qemu? /
[1] https://copy.sh/v86/ https://github.com/copy/v86
[0]: https://github.com/copy/v86