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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.mel.connect.com.au!news.mel.aone.net.au!grumpy.fl.net.au!news.webspan.net!ix.netcom.com!netcom.net.uk!dispatch.news.demon.net!demon!arg1.demon.co.uk!not-for-mail From: Andrew Gordon <andrew.gordon@net-tel.co.uk> Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Accessing i/o-ports from user-code ? Date: Tue, 31 Dec 1996 11:42:19 +0000 Lines: 16 Message-ID: <32C8FC1B.41C67EA6@net-tel.co.uk> References: <87g20rbmk6.fsf@acme1.ruhr.de> <5a9eom$huj@uriah.heep.sax.de> NNTP-Posting-Host: arg1.demon.co.uk X-NNTP-Posting-Host: arg1.demon.co.uk X-Mailer: Mozilla 3.01Gold (X11; I; FreeBSD 2.1.5-RELEASE i386) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:33405 J Wunsch wrote: > > Christoph Haas <chris@acme1.ruhr.de> wrote: > > > I need to access i/o-ports from within my application. I wanted to use > > inb() and outb() to send bytes to a certain port that is used by an > > isa card, but I got a bus error. Do I need special permissions to > > access the ports... > > Yes. You need to keep a filedescriptor open on /dev/io for this. If > you're going to make your binary setuid root for this purpose, be > careful to drop permissions as soon as possible. Note that you still need to be very careful even having reverted to some other uid - the I/O access permissions are inherited by child processes.