OpenBSD and FreeBSD aren't compatible with each other. Having FreeBSD would certainly make porting simpler, as the two are more alike that say Linux and OpenBSD

OpenBSD and FreeBSD aren't compatible with each other. Having FreeBSD would certainly make porting simpler, as the two are more alike that say Linux and OpenBSD, or Windows and OpenBSD. If you browse through the dotnet runtime code, you'll see that all the supported operating systems have code added to specifically support them. It's not much different than Java, the compiler targets an intermediate platform (JVM for Javva, CIL for C#/F#,VB.Net. The runtime needs to be ported and there's operating system specific code in the source for the runtime for all the supported operating system.