This seems not correct to me. No one has made RVC "mandatory". For a start no one had any authority to do any such thing! Some people building Linux-capable pr

This seems not correct to me. No one has made RVC "mandatory". For a start no one had any authority to do any such thing! Some people building Linux-capable processors decided to include RVC. Some people with Linux distributions (Fedora, Debian), seeing that all known current efforts to build linux capable processors were supporting RVC, and seeing the large benefits it provides, decided to build their distros using RVC. If someone wants a Linux distro that doesn't use RVC .. it's not a problem. The instructions supported are exactly the same. There are no portability problems. If a package will build successfully with RVC then it will compile without it, no problem, with no additional human work. Just change one configure flag when you build the compiler (to default to rv64g instead of rv64gc). The only difference is the binaries will all be 30% to 50% bigger. Some more build machines will be required, and a few GB of disk space. Theses are trivial things. It's absolutely nothing like the difference between, say, armeabi and armhf or the differences between armv4, armv4t, armv5, armv6, armv7.