Date: Sat, 30 Dec 1995 20:48:10 -0800 From: "Amancio Hasty Jr." <hasty@rah.star-gate.com> To: Sujal Patel <smpatel@wam.umd.edu> Cc: David Dawes <dawes@rf900.physics.usyd.edu.au>, "Jordan K. Hubbard" <jkh@time.cdrom.com>, hackers@freebsd.org Subject: Re: /dev/io Message-ID: <199512310448.UAA00410@rah.star-gate.com> In-Reply-To: Your message of "Sat, 30 Dec 1995 23:18:14 EST." <Pine.BSF.3.91.951230231022.242A-100000@sl-046.sl.cybercomm.net>
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>>> Sujal Patel said: > 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. > I implemented i/o bitmap permissions way back for 386bsd you may be able to get the original patches if you search minnies mail archive. Yes, I know that the patches would not apply to the current kernel however for anyone interested it would show how it was done. Have fun, Amancio
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