I can tell you some of that. We ported all our applications from QNX6.5 to QNX6.6 and then QNX7.0. They deprecated some POSIX calls like posix_spawn_file_actio

I can tell you some of that. We ported all our applications from QNX6.5 to QNX6.6 and then QNX7.0. They deprecated some POSIX calls like posix_spawn_file_actions_addopen (at least in QNX6.6 documentation they mention it's not fully implemented and it is indeed broken). They made the QNX7.0 kernel instrumented-only (there are no longer non-instrumented versions). They changed lots of low level stuff that is outside the kernel, like throwing out photon and replacing it with screen library, completely replacing the PCI server, making changes to the console, security patches, and so on. But since it's a microkernel, this is mostly in userland.