The choice of MIT for a kernel feels like setting up the project to be cannibalized rather than contributed to.
We've seen this movie before with the BSDs. Hardware vendors love permissive licenses because they can fork, add their proprietary HAL/drivers, and ship a closed binary blob without ever upstreaming a single fix.
Linux won specifically because the GPL forced the "greedy" actors to collaborate. In the embedded space, an MIT kernel is just free R&D for a vendor who will lock the bootloader anyway.
Not sure why am getting in the middle of this but I need to point out that you are not even correct for Linux.
Linux rather famously has avoided the GPL3 and is distributed under a modified GPL2. This license allows binary blob modules. We are all very familiar with this.
As a result, the kernel that matches your description above that ships in the highest volume is Linux by a massive margin. Can you run a fully open source Linux kernel on your Android phone? Probably not. You do not have the drivers. You may not pass the security checks.
Do companies like Broadcomm “collaborate” on Linux even in the PC or Mac space? Not really.
On the other side, companies that use FreeBSD do actually contribute a lot of code. This includes Netflix most famously but even Sony gives back.
The vast majority of vendors that use Linux embedded never contribute a single line of code (like 80% or more at least - maybe 98%). Very few of them even make the kernel code they use available. I worked in video surveillance where every video recorder and camera in the entire industry is Linux based at this point. Almost none of them distribute source code.
But even the story behind the GPL or not is wrong in the real world.
You get great industry players like Valve that contribute a lot of code. And guess what, a lot of that code is licensed permissively. And a lot of other companies continue to Mesa, Wayland, Xorg, pipewire, and other parts of the stack that are permissively licensed. The level of contribution has nothing to do with the GPL.
How about other important projects? There are more big companies contributing to LLVM/Clang (permissive) than there are to GCC (GPL).
In fact, the GPL often discourages collaboration. Apple is a great example of a company that will not contribute to even the GPL projects that they rely on. But they do contribute a fair bit of Open Source code permisssively. And they are not even one of the “good guys” in Open Source.
This comment is pure ideological mythology.
I think GCC is the real shining example of a GPL success, it broke through a rut of high cost developer tooling in the 1990s and became the de facto compiler for UNIX and embedded BSPs (Board Support Packages) while training corporations on how to deal with all this.
But then LLVM showed up and showed it is no longer imperative to have a viral license to sustain corporate OSS. That might've not been possible without the land clearing GCC accomplished, but times are different now and corporations have a better understanding and relationship with OSS.
The GPL has enough area to opt out of contributing (i.e. services businesses or just stacking on immense complexity in a BSP so as to ensure vendor lockin) that it isn't a defining concern for most users.
Therefore I don't think Linux' success has much to do with GPL. It has been effective in the BSP space, but the main parts most people care about and associate with Linux could easily be MIT with no significant consequence on velocity and participation. In fact, a lot of the DRM code (graphics drivers) are dual-licensed thusly.
This comment does not contribute to discussion of TFA: it's just license flamewar bait.
The authors almost certainly gave a bit of thought to their choice of license. The choice of license is a "business choice" that has to do with the author(s)' goals, and it is a choice best seen as intending to achieve those goals. Those goals can be very different from your own goals, and that's fine! There is no need to shame TFA for their choice of license, or implicitly for their goals as opposed to yours.
Not meaning to single you out specifically, but this entire discussion — all of this license gatekeeping is ridiculous. This is a very cool project, but if the license ruins it for you, there are zillions of open source GPL3 kernels.
I mean, this is not different from bitching about someone writing their custom kernel in C++ instead of Rust, or Zig. It’s not your project! Let people do their own thing! MIT is a perfectly fine license; maybe the lack of zealotry associated with it would even be a positive thing for whatever community might be built around this eventually, if the author is even interested in having other contributions.
That's 1980s-90s thinking. Nobody is making proprietary BSD forks any more and new kernels probably have no chance of reaching production anyway so worrying about proprietary forks is irrelevant.
> Linux won specifically because the GPL forced the "greedy" actors to collaborate.
How do we know that? It seems to me that a greater factor in the success of Linux was the idealism and community. It was about freedom. Linux was the "Revolution OS" and the hacker community couldn't but fall in love with Linux and its community that embodied their ideals. They contributed to it and they founded new kinds of firms that (at least when they began) committed themselves to respect those principles.
I realise the memory of Linux's roots in hacker culture is fading away fast but I really do think this might have been the key factor in Linux's growth. It reached a critical mass that way.
I'm quite certain of the fact that this was more important anyway than the fact that, for instance, Linksys had to (eventually! they didn't at first) release the source code to their modifications to the Linux kernel to run on the WRT54G. I don't think things like that played much of a role at all.
Linksys were certainly kind enough to permit people to flash their own firmware to that router, and that helped grow Linux in that area. They even released a special WRT54GL edition to facilitate custom firmware. But they could just as easily have Tivoised it (something that the Linux licence does not forbid) and that would've been the end of the story.