[jonhohle]

    > (1) linux does not go out of its way to provide stable ABI's, which makes porting proprietary software to linux and maintaining it there expensive

My impression is that the opposite is true for user space - https://yarchive.net/comp/linux/gcc_vs_kernel_stability.html Maybe you're referring to GNU or kernel modules? There are more than a few anecdotes of people running 20+ year old binaries that still work with X11.

[trasz]

Linux keeps the userspace<->kernel ABI stable, sure. But that's largely an implementation detail; what matters is the ABI presented to applications - at the library level, not underneath libc. And this varies between libraries and distributions.