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Newsgroups: comp.os.386bsd.questions
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From: veit@fanoe.gmd.de (Holger Veit)
Subject: Re: Equivalent to iopl(3) in 386BSD
Message-ID: <1993Mar1.161613.21892@gmd.de>
Sender: veit@fanoe (Holger Veit)
Nntp-Posting-Host: fanoe
Organization: GMD - German National Research Center for Computer Science
References: <1993Mar1.140349.12114@lth.se>
Date: Mon, 1 Mar 1993 16:16:13 GMT
Lines: 31
In article <1993Mar1.140349.12114@lth.se>, jh@efd.lth.se (Joergen Haegg) writes:
|>
|> Is there any replacement for the linux-function iopl(3)?
|> Seems to be support thru the psl.h headerfile, but
|> what function should I use?
|>
|> #define PSL_IOPL 0x00003000 /* i/o priviledge level enable */
|>
|>
|> --
|> Joergen Haegg jh@efd.lth.se
Normal processes run at ring 3, to get I/O access, for instance,
you need privilege ring 0. This is implemented for the Xserver as
a special hack. With pccons (+Xserver-patches), there are functions
CONSOLE_X_MODE_ON/OFF, which do this, but have the disadvantage
of switching the keyboard into a probably unwanted mode, codrv
has the switcher ioctl CONSOLE_X_MODE (arg=0 => ring 3,
arg=1 => ring 0), without influence on the keyboard. There is an
intentional protection, which requires the process executing this
function to run setuid-root.
Holger
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