Consecutive FFI calls

[David Turner]

(cross-posted from ghc-dev and the cafe, with apologies to cross-subscribers)

Hi,

If I make a sequence of FFI calls (on a single Haskell thread) but
which end up being called from different OS threads, is there any kind
of ordering guarantee given? More specifically, is there a full memory
barrier at the point where a Haskell thread migrates to a new OS
thread?

Many thanks,

David