> Another regression I'm seeing: while `ps -ax' showed all system
> processes when running the pre-merge kernel, it only shows [system]
> on the post-merge kernel. I'm still using pre-merge userland, though:

This one is because the system processes are no longer processes, but
threads. Try appending the '-s' flag to ps(1). If you have a fairly new
top(1) you can press 't' to see various threads in proc0.