The code doesn't really seem to use any kernel functionality other than spinlocks/mutexes and waiting and waking up tasks. That same code should be portable to

The code doesn't really seem to use any kernel functionality other than spinlocks/mutexes and waiting and waking up tasks. That same code should be portable to userspace by: - Allocating everything into shared memory, where the shared memory fd replaces the ntsync device fd - Using an index into a global table of object pointers instead of object fds - Using futex-based mutexes instead of kernel spinlocks - Using a futex-based parking/unparking system like parking_lot does Obviously this breaks if the shared memory is corrupted or if you SIGKILL any process while it's touching it, but for Wine getting that seems acceptable. A kernel driver is clearly better though for this reason.