From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from imperial.edgeglobal.com (imperial.edgeglobal.com [208.197.226.14]) by edgeglobal.com (8.9.1/8.9.1) with ESMTP id KAA06997 for ; Mon, 4 Oct 1999 10:34:17 -0400 Date: Mon, 4 Oct 1999 10:38:13 -0400 (EDT) From: James Simmons Subject: MMIO regions Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Linux MM List-ID: Howdy again!! I noticed something for SMP machines with all the dicussion about concurrent access to memory regions. What happens when you have two processes that have both mmapped the same MMIO region for some card. Doesn't have to be a video card,. On a SMP machine it is possible that both processes could access the same region at the same time. This could cause the card to go into a indeterminate state. Even lock the machine. Does their exist a way to handle this? Also some cards have mulitple MMIO regions. What if a process mmaps one MMIO region of this card and another process mmaps another MMIO region of this card. Now process one could alter the card in such a way it could effect the results that process two is expecting. How is this dealt with? Is it dealt with? If not what would be a good way to handle this? -- 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/