@hierkiosk @mcc I wouldn't be surprised if libc was doing a lot of heavy lifting there. I also wouldn't be surprised that for relatively simple applications there wouldn't be any problems with running a program that was statically compiled for 2.6.x on 5.x or 6.x kernels. However, I doubt it'll be easy to run a program compiled and linked for 5.x kernel on an older kernel. Stuff like that is a problem for both emulation layers (NetBSD compat_linux and FreeBSD Linuxulator) and hard forks (that will either have to stay somewhat frozen in time or will have to catch up to the upstream). E.g. let's say Valve ships a new Steam version that requires kernel 7.2 - this will happen almost inevitably; how much work will be needed to figure out what parts of the Linux 7.2 need to be re-implemented in the fork and in the emulators?