While it's part of upstream Linux, many kernels come with it disabled because it has a long history of security issues and basically nothing but Android uses it.
It also liked to trigger kernel panics for me on Ubuntu 22.04, but that could be a weird hardware issue.
Ah, interesting...man, software is fun. I wouldn't have guessed in a million years that it could cause panics as an optional component, like, it shouldn't be running code unless it is being used, and it shouldn't be called because it isn't mandatory in the kernel.
I guess I'm still grokking software complexity, Linux, and how much work an OS is truly is, 25 years after I built my first Linux box...because in another sense, of course that could happen.
A binder transaction behaves sort of like a syscall, in the sense that a client process can immediately, synchronously transfer control to a server thread, rather than just enqueueing a message to be processed whenever the server gets around to it.
This enables Android to separate many of its components into different processes (at different privilege levels), and use binder for RPCs that are on the "critical path" for user interaction, without incurring impractical amounts of overhead or latency.
