[Haskell-cafe] Unbound threads and FFI

How do unbound threads play with FFI? According to Simon PJ, each foreign call will get its own OS thread if its blocked. How does GHC determine if the call is blocked? Does each call get its own OS thread from the start? Sometime later? Does this depend on the safe/unsafe specs of the foreign call? Does the above change if a threaded/non-threaded runtime is in use? Thanks, Joel -- http://wagerlabs.com/