yea, but that does not satisfy my requirements: 1) My driver have the buffer available before any apps start 2) The buffer be persistent when apps come and go. Maybe something is far easier, but it is not of use if it doesn't meet the requirements. So, is what I ask for doable or not? Scott At 10:19 AM 6/6/2002, you wrote: G'day Scott, At 18:08 -0700 02-6-5, Scott Taggart wrote: Hi, I have seen various posts, responses, etc. on this subject, but quite frankly, I got lost. I have the need to take a slug of kernel memory in my driver and make it available to my user app so that my app can access it directly (I'll take care of arbitration and protection with my driver). Can someone give me the simplest set of calls I need to do this? I am willing to research the calls but just need the general set of calls required and order they should be called along with the appropriate caveats. The memory I need to map to user land is allocated by my driver at startup and is wired. As Jim said it is usually better to map user memory into the kernel and have the driver wire and unwire it. You don't really have to worry about the app aborting without your being aware of it as the act of wiring means that the memory stays valid until the DRIVER is ready to get rid of it. By far the easiest way of doing this sort of thing is to pass a buffer in with an open style routine. Wrap it in a memory descriptor and register it with your driver. Your driver can then prepare() (i.e. wire) it and map() it to get a virtual address to access the memory. Now is also a good time to grab the physical addresses for any future DMA you may want to do. Godfrey _______________________________________________ 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.