Excuse me, what thread are you trying to block in the kernel? What sort of driver are you writing? In general we do not allow what you are trying to do. Godfrey At 13:02 -0400 03-4-30, Dave Koziol wrote: I've found this routine in ipc_mig.c, and it looks like it does exactly what I want to do for a particular project, but I haven't been able to find any code which actually uses it. Can anyone point out anywhere in Darwin where this is used? Is this a "safe" facility to use? I need to perform some RPC calls from a KEXT into a user process, and block waiting for the results. This routine appears to do exactly that... Thanks for any pointers in the right direction, _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.