Which platforms do/do not support cpu time profiling?

[Glenn Morris]

etc/NEWS says:

  ** New sampling-based Elisp profiler.
  [...]
  The sampling rate can be based on CPU time (only supported on some
  systems)..


Which are the platforms which do/do not support this?


There is a configure option --enable-profiling which you might think has
something to do with this, but it doesn't. Is that option still useful,
and if so can someone come up with a more informative description for it
than "build emacs with profiling support"?