projects / thirdparty / man-pages.git / blame
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1 | .\" Hey Emacs! This file is -*- nroff -*- source. |
| 2 | .\" | |
| 3 | .\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu) | |
| 4 | .\" Portions extracted from linux/kernel/ioport.c (no copyright notice). | |
| 5 | .\" | |
| 6 | .\" Permission is granted to make and distribute verbatim copies of this | |
| 7 | .\" manual provided the copyright notice and this permission notice are | |
| 8 | .\" preserved on all copies. | |
| 9 | .\" | |
| 10 | .\" Permission is granted to copy and distribute modified versions of this | |
| 11 | .\" manual under the conditions for verbatim copying, provided that the | |
| 12 | .\" entire resulting derived work is distributed under the terms of a | |
| 13 | .\" permission notice identical to this one. | |
| 14 | .\" | |
| 15 | .\" Since the Linux kernel and libraries are constantly changing, this | |
| 16 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
| 17 | .\" responsibility for errors or omissions, or for damages resulting from | |
| 18 | .\" the use of the information contained herein. The author(s) may not | |
| 19 | .\" have taken the same level of care in the production of this manual, | |
| 20 | .\" which is licensed free of charge, as they might when working | |
| 21 | .\" professionally. | |
| 22 | .\" | |
| 23 | .\" Formatted or processed versions of this manual, if unaccompanied by | |
| 24 | .\" the source, must acknowledge the copyright and authors of this work. | |
| 25 | .\" | |
| 26 | .\" Modified Tue Aug 1 16:47 1995 by Jochen Karrer | |
| 27 | .\" <cip307@cip.physik.uni-wuerzburg.de> | |
| 28 | .\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com> | |
| 29 | .\" Modified Fri Nov 27 14:50:36 CET 1998 by Andries Brouwer <aeb@cwi.nl> | |
| 30 | .\" Modified, 27 May 2004, Michael Kerrisk <mtk16@ext.canterbury.ac.nz> | |
| 31 | .\" Added notes on capability requirements | |
| 32 | .\" | |
| 33 | .TH IOPL 2 2004-05-27 "Linux 2.6.6" "Linux Programmer's Manual" | |
| 34 | .SH NAME | |
| 35 | iopl \- change I/O privilege level | |
| 36 | .SH SYNOPSIS | |
| 37 | .B #include <sys/io.h> | |
| 38 | .sp | |
| 39 | .BI "int iopl(int " level ); | |
| 40 | .SH DESCRIPTION | |
| 41 | .B iopl | |
| 42 | changes the I/O privilege level of the current process, as specified in | |
| 43 | .IR level . | |
| 44 | ||
| 45 | This call is necessary to allow 8514-compatible X servers to run under | |
| 46 | Linux. Since these X servers require access to all 65536 I/O ports, the | |
| 47 | .B ioperm | |
| 48 | call is not sufficient. | |
| 49 | ||
| 50 | In addition to granting unrestricted I/O port access, running at a higher | |
| 51 | I/O privilege level also allows the process to disable interrupts. This | |
| 52 | will probably crash the system, and is not recommended. | |
| 53 | ||
| 54 | Permissions are inherited by fork and exec. | |
| 55 | ||
| 56 | The I/O privilege level for a normal process is 0. | |
| 57 | ||
| 58 | This call is mostly for the i386 architecture. | |
| 59 | On many other architectures it does not exist or will always | |
| 60 | return an error. | |
| 61 | .SH "RETURN VALUE" | |
| 62 | On success, zero is returned. On error, \-1 is returned, and | |
| 63 | .I errno | |
| 64 | is set appropriately. | |
| 65 | .SH ERRORS | |
| 66 | .TP | |
| 67 | .B EINVAL | |
| 68 | .I level | |
| 69 | is greater than 3. | |
| 70 | .TP | |
| 71 | .B ENOSYS | |
| 72 | This call is unimplemented. | |
| 73 | .TP | |
| 74 | .B EPERM | |
| 75 | The calling process has insufficient privilege to call | |
| 76 | .BR iopl ; | |
| 77 | the | |
| 78 | .B CAP_SYS_RAWIO | |
| 79 | capability is required. | |
| 80 | .SH "CONFORMING TO" | |
| 81 | \fBiopl\fP is Linux specific and should not be used in processes | |
| 82 | intended to be portable. | |
| 83 | .SH NOTES | |
| 84 | Libc5 treats it as a system call and has a prototype in | |
| 85 | .IR <unistd.h> . | |
| 86 | Glibc1 does not have a prototype. Glibc2 has a prototype both in | |
| 87 | .I <sys/io.h> | |
| 88 | and in | |
| 89 | .IR <sys/perm.h> . | |
| 90 | Avoid the latter, it is available on i386 only. | |
| 91 | .SH "SEE ALSO" | |
| 92 | .BR ioperm (2), | |
| 93 | .BR capabilities (7) |