I found this statement from Linus in that thread; "It's not that the kernel ABI (with all the system calls, all the /proc files, all the ioctl's, etc) is set i

I found this statement from Linus in that thread; "It's not that the kernel ABI (with all the system calls, all the /proc files, all the ioctl's, etc) is set in stone and "sacred". Absolutely anything can be changed, wildly. But if it turns out that applications (or hardware) that people use end up breaking noticeably, then that is a regression."