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Diffstat (limited to 'man2/iopl.2')
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diff --git a/man2/iopl.2 b/man2/iopl.2 new file mode 100644 index 000000000..3f07dbeac --- /dev/null +++ b/man2/iopl.2 @@ -0,0 +1,93 @@ +.\" Hey Emacs! This file is -*- nroff -*- source. +.\" +.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu) +.\" Portions extracted from linux/kernel/ioport.c (no copyright notice). +.\" +.\" Permission is granted to make and distribute verbatim copies of this +.\" manual provided the copyright notice and this permission notice are +.\" preserved on all copies. +.\" +.\" Permission is granted to copy and distribute modified versions of this +.\" manual under the conditions for verbatim copying, provided that the +.\" entire resulting derived work is distributed under the terms of a +.\" permission notice identical to this one. +.\" +.\" Since the Linux kernel and libraries are constantly changing, this +.\" manual page may be incorrect or out-of-date. The author(s) assume no +.\" responsibility for errors or omissions, or for damages resulting from +.\" the use of the information contained herein. The author(s) may not +.\" have taken the same level of care in the production of this manual, +.\" which is licensed free of charge, as they might when working +.\" professionally. +.\" +.\" Formatted or processed versions of this manual, if unaccompanied by +.\" the source, must acknowledge the copyright and authors of this work. +.\" +.\" Modified Tue Aug 1 16:47 1995 by Jochen Karrer +.\" <cip307@cip.physik.uni-wuerzburg.de> +.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com> +.\" Modified Fri Nov 27 14:50:36 CET 1998 by Andries Brouwer <aeb@cwi.nl> +.\" Modified, 27 May 2004, Michael Kerrisk <mtk16@ext.canterbury.ac.nz> +.\" Added notes on capability requirements +.\" +.TH IOPL 2 2004-05-27 "Linux 2.6.6" "Linux Programmer's Manual" +.SH NAME +iopl \- change I/O privilege level +.SH SYNOPSIS +.B #include <sys/io.h> +.sp +.BI "int iopl(int " level ); +.SH DESCRIPTION +.B iopl +changes the I/O privilege level of the current process, as specified in +.IR level . + +This call is necessary to allow 8514-compatible X servers to run under +Linux. Since these X servers require access to all 65536 I/O ports, the +.B ioperm +call is not sufficient. + +In addition to granting unrestricted I/O port access, running at a higher +I/O privilege level also allows the process to disable interrupts. This +will probably crash the system, and is not recommended. + +Permissions are inherited by fork and exec. + +The I/O privilege level for a normal process is 0. + +This call is mostly for the i386 architecture. +On many other architectures it does not exist or will always +return an error. +.SH "RETURN VALUE" +On success, zero is returned. On error, \-1 is returned, and +.I errno +is set appropriately. +.SH ERRORS +.TP +.B EINVAL +.I level +is greater than 3. +.TP +.B ENOSYS +This call is unimplemented. +.TP +.B EPERM +The calling process has insufficient privilege to call +.BR iopl ; +the +.B CAP_SYS_RAWIO +capability is required. +.SH "CONFORMING TO" +\fBiopl\fP is Linux specific and should not be used in processes +intended to be portable. +.SH NOTES +Libc5 treats it as a system call and has a prototype in +.IR <unistd.h> . +Glibc1 does not have a prototype. Glibc2 has a prototype both in +.I <sys/io.h> +and in +.IR <sys/perm.h> . +Avoid the latter, it is available on i386 only. +.SH "SEE ALSO" +.BR ioperm (2), +.BR capabilities (7) |