Yes. "We assume and rely on system call X being implemented" is another common case. In particular, glibc will check your kernel version and won't run if it is

Yes. "We assume and rely on system call X being implemented" is another common case. In particular, glibc will check your kernel version and won't run if it is too old for what it was built against: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/dl-osinfo.h;h=823cd8224df939134018fbd8f0227e9f501393ab;hb=HEAD#l42 https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/uni... (Comments in that code notwithstanding, I think that the glibc configure will always define a minimum kernel version: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/configure.ac;h=13abda0a51484c5951ffc6d718aa36b72f3a9429;hb=HEAD#l36 https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/uni... and so the check always happens.)