From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 4 Oct 1999 13:27:43 -0400 (EDT) From: James Simmons Subject: Re: MMIO regions In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: "Benjamin C.R. LaHaise" Cc: Linux MM List-ID: On Mon, 4 Oct 1999, Benjamin C.R. LaHaise wrote: > On Mon, 4 Oct 1999, James Simmons wrote: > > > And if the process holding the locks dies then no other process can access > > this resource. Also if the program forgets to release the lock you end up > > with other process never being able to access this piece of hardware. > > Eh? That's simply not true -- it's easy enough to handle via a couple of > different means: in the release fop or munmap which both get called on > termination of a task. Which means only one application can ever have access to the MMIO. If another process wanted it then this application would have to tell the other appilcation hey I want it so unmap. Then the application demanding it would then have to mmap it. > Or in userspace from the SIGCHLD to the parent, Thats assuming its always a child that has access to a MMIO region. > or if you're really paranoid, you can save the pid in an owner field in the > lock and periodically check that the process is still there. How would you use this method? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/