> Wouldn't it be easier to just use a simpler POSIX-like OS to begin with?
It would be simpler, but harder.
The point of the linux kernel is that it's familiar. Many developers know it from inside, many wrote device drivers or file systems, its network stack is well-understood. There's plenty of reference and expertise.
POSIX is an ancient standard, which, while still useful, does not give you enough to be able to just switch to another compliant OS. Say, io_uring is not POSIX, and EBPF is not POSIX, and both can be hugely important for your embedded system.
With that, you can still run multiple threads with that highly minimal nolibc (not pthreads, but clone() is supported), AFAICT, so you can use a complex architecture. I didn't notice if cgroups are surfaced; with them, you'd be able to add defense in depth.
This is on top of Linux's superior tooling, compilers, a collection of drivers for nearly everything, and other creature comforts, usually FOSS.
It would be simpler, but harder.
The point of the linux kernel is that it's familiar. Many developers know it from inside, many wrote device drivers or file systems, its network stack is well-understood. There's plenty of reference and expertise.
POSIX is an ancient standard, which, while still useful, does not give you enough to be able to just switch to another compliant OS. Say, io_uring is not POSIX, and EBPF is not POSIX, and both can be hugely important for your embedded system.
With that, you can still run multiple threads with that highly minimal nolibc (not pthreads, but clone() is supported), AFAICT, so you can use a complex architecture. I didn't notice if cgroups are surfaced; with them, you'd be able to add defense in depth.
This is on top of Linux's superior tooling, compilers, a collection of drivers for nearly everything, and other creature comforts, usually FOSS.