Date: Sat, 30 Dec 1995 23:18:14 -0500 (EST) From: Sujal Patel <smpatel@wam.umd.edu> To: David Dawes <dawes@rf900.physics.usyd.edu.au> Cc: "Jordan K. Hubbard" <jkh@time.cdrom.com>, hackers@freebsd.org Subject: Re: /dev/io Message-ID: <Pine.BSF.3.91.951230231022.242A-100000@sl-046.sl.cybercomm.net> In-Reply-To: <199512310311.OAA16531@rf900.physics.usyd.edu.au>
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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
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