tock VS linux

Hi! This is Daniel from OxidOS Automotive (stating this for disclaimer purposes).

Yes, our OS is based on TockOS, and our CEO (Alex Radovici) is #7 in the contributors list (https://github.com/tock/tock/graphs/contributors), with other colleagues contributing in the past years.

I'm definitely not the best person to answer this, but honestly it's not bad. Here's an example of a moderately complex peripheral, the cortex-m MPU, and how one rust OS handles it:

https://github.com/tock/tock/blob/3a0527d586702b8ae8cb242391...

Reads and writes turn into volatile reads, so everything works out under the hood. You get the benefits of everything having good names, declared sizes, and proper typing on your register accesses. You can extend that to bit accesses as well.

Rust still has a few areas it isn't competitive in, like your hyper limited or obscure chips (e.g. 8051s, XAP), mature tooling around formal methods, and a certification story for safety critical code. People are working on these latter two issues (e.g. ferrocene) and supposedly very close to public delivery, but you know how slow the industry is to adopt new things even then.

There's Tock (https://www.tockos.org/), which is written in Rust (with sprinkles of assembly).

Yeah, and I like I mentioned in the earlier comment, omitting the frame pointer reduces code size by 10% on RISC-V targets, which is huge when dealing with embedded flash: https://github.com/tock/tock/pull/1660

Tock is an excellent embedded OS written in Rust and has some good industrial support. I think Tock gets a lot of stuff right and I highly recommend some of the talks the developers gave on it.

Unfortunately, it increases the code size by 10%. I was looking into this just last week, and can confirm that it's still a problem on the latest version of Rust nightly: https://github.com/tock/tock/pull/1660

I wish we could have frame pointers, because they would make working in embedded land so much easier and more reliable, but a 10% increase in code size just isn't worth it.

TockOS was the first rust RTOS I found. Coincidentally, it has had support for the esp32c3 for over a year now.

FFS predates FreeBSD and is in some capacity supported by all 3 major BSDs. I'm fairly confident that Linux actually supports it through the ufs driver ( https://github.com/torvalds/linux/tree/master/fs/ufs ); whether the use of different names in different places makes it better or worse is an exercise for the reader.

These are a bit easier to see what's going on:

https://github.com/torvalds/linux/commit/d5cf50dafc9dd5faa1e...

https://github.com/torvalds/linux/blob/d5cf50dafc9dd5faa1e61...

Unfortunately Github doesn't have a way to render symbols for whitespace, but you can tell by selecting the spaces that the previous version had leading tabs. Linus changed it so that the tokens `default` and the number e.g. `12` are also separated by a tab. This is tricky, because the token "default" is seven characters, it will always give this added tab a width of 1 char which makes it always layout the same as if it were a space no matter if you use tab widths of 1, 2, 4, or 8.

There was also a Gentoo effort to run atop FreeBSD[0]. The challenge of course is that afaik none of the BSD kernel ABIs are considered stable. The stable interface is the BSD libc. That said, with binfmt_misc, I don't see a reason you couldn't just run (at least some) FreeBSD binaries on Linux with a thin syscall translation layer (rather something like qemu-system) and then your layer hooked via binfmt_misc. I'm not aware of anyone who has done this for FreeBSD, but prior efforts existed as alternate binfmts for SysVr4/5 ELF binaries[2]. Either way would take some elbow grease, but you *might* even be able just reuse binfmt_elf and just have a new interpreter for FreeBSD elf.

[0] https://wiki.gentoo.org/wiki/Gentoo_FreeBSD

[1] https://docs.kernel.org/admin-guide/binfmt-misc.html

[2] https://github.com/torvalds/linux/blob/master/fs/binfmt_elf....

> The original less-than check was deemed incorrect

It was only deemed incorrect because of an information leak. Not because it's a valid use-case for user space to copy smaller portions of *hwrpb into user space. https://github.com/torvalds/linux/commit/21c5977a836e399fc71...

Correct. And the combined work needs to carry the MIT license text and copyright attributions for the MIT software authors. With binary distribution it must also be overt, not hidden in some source code drop, but directly accompanying the binary.

Many people who talk about relicensing never credit the MIT developers or distribute the MIT license text. "Because it's GPL now."

I don't think that you believe that, but many developers do.

Some don't see the need for source code scans for Open Source compliance, because the license.txt says GPL, so it's GPL. Prime example is the Linux kernel. There is code under different licenses in there, but people don't even read https://github.com/torvalds/linux/blob/master/COPYING till the end ("In addition, other licenses may also apply.") and conclude it's simply GPL 2 and nothing else.

Also be aware that sublicensing is not the same as relicensing.

> Does he have something against it?

He notoriously hates GNU Emacs, yes.

https://marc.info/?m=122955159617722

https://github.com/torvalds/linux/blob/master/Documentation/...

So If we would only count code and not comments, it is only 9489 LoC Rust. Which would be about 0.03% and if we take all lines and not only LoC it would be around 0.05%

[0] https://github.com/XAMPPRocky/tokei

[1] https://github.com/torvalds/linux/commit/b401b621758e46812da...

AIUI fsync is built on futex_waitv which has been upstreamed. So this has to be more than that.

https://github.com/torvalds/linux/commit/a0eb2da92b715d0c97b...