From owner-freebsd-hackers Sat Dec 30 20:19:10 1995 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id UAA05546 for hackers-outgoing; Sat, 30 Dec 1995 20:19:10 -0800 (PST) Received: from localhost.cybercomm.net (sl-046.sl.cybercomm.net [199.171.196.174]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id UAA05539 for ; Sat, 30 Dec 1995 20:19:03 -0800 (PST) Received: from sl-046.sl.cybercomm.net (localhost [127.0.0.1]) by localhost.cybercomm.net (8.6.12/8.6.12) with SMTP id XAA00337; Sat, 30 Dec 1995 23:18:15 -0500 Date: Sat, 30 Dec 1995 23:18:14 -0500 (EST) From: Sujal Patel X-Sender: smpatel@sl-046.sl.cybercomm.net To: David Dawes cc: "Jordan K. Hubbard" , hackers@freebsd.org Subject: Re: /dev/io In-Reply-To: <199512310311.OAA16531@rf900.physics.usyd.edu.au> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-hackers@freebsd.org Precedence: bulk On Sun, 31 Dec 1995, David Dawes wrote: > >I think a few X servers would definitely break of /dev/io went away > >suddently, but I also see no reason why the other interface couldn't > >be implemented in parallel with a change-over at some point in the > >future. > > For what it's worth, the XFree86 servers get I/O permission by using > the KDENABIO ioctl in the console driver rather than by opening /dev/io. I wasn't even aware that this existed, but looking at the Xserver source it seems like BSDI, Linux, FreeBSD, and NetBSD all have it (but only Free/NetBSD use it for Xserver IO permission). This makes it even easier to phase out /dev/io, because the Xservers will not break and the code for iopl() would be very similar to the code for the KDENABIO ioctl. The only non-trivial thing would be implementing IO permission bitmaps, but I'm not even sure if it's worth it since it would be a rarely used feature. Sujal