183 lines
4.0 KiB
HTML
183 lines
4.0 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of IOPERM</TITLE>
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</HEAD><BODY>
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<H1>IOPERM</H1>
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Section: Linux Programmer's Manual (2)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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ioperm - set port input/output permissions
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>#include <<A HREF="file:///usr/include/sys/io.h">sys/io.h</A>></B>
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/* for glibc */
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<P>
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<B>int ioperm(unsigned long </B><I>from</I><B>, unsigned long </B><I>num</I><B>, int </B><I>turn_on</I><B>);</B>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<B>ioperm</B>()
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sets the port access permission bits for the calling thread for
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<I>num</I>
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bits starting from port address
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<I>from</I>.
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If
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<I>turn_on</I>
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is nonzero, then permission for the specified bits is enabled;
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otherwise it is disabled.
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If
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<I>turn_on</I>
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is nonzero, the calling thread must be privileged
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(<B>CAP_SYS_RAWIO</B>).
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<P>
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Before Linux 2.6.8,
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only the first 0x3ff I/O ports could be specified in this manner.
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For more ports, the
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<B><A HREF="/cgi-bin/man/man2html?2+iopl">iopl</A></B>(2)
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system call had to be used (with a
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<I>level</I>
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argument of 3).
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Since Linux 2.6.8, 65,536 I/O ports can be specified.
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<P>
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Permissions are inherited by the child created by
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<B><A HREF="/cgi-bin/man/man2html?2+fork">fork</A></B>(2)
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(but see NOTES).
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Permissions are preserved across
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<B><A HREF="/cgi-bin/man/man2html?2+execve">execve</A></B>(2);
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this is useful for giving port access permissions to unprivileged
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programs.
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<P>
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This call is mostly for the i386 architecture.
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On many other architectures it does not exist or will always
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return an error.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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On success, zero is returned.
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On error, -1 is returned, and
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<I>errno</I>
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is set appropriately.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<DL COMPACT>
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<DT id="1"><B>EINVAL</B>
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<DD>
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Invalid values for
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<I>from</I>
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or
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<I>num</I>.
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<DT id="2"><B>EIO</B>
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<DD>
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(on PowerPC) This call is not supported.
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<DT id="3"><B>ENOMEM</B>
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<DD>
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Out of memory.
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<DT id="4"><B>EPERM</B>
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<DD>
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The calling thread has insufficient privilege.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>CONFORMING TO</H2>
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<B>ioperm</B>()
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is Linux-specific and should not be used in programs
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intended to be portable.
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<A NAME="lbAH"> </A>
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<H2>NOTES</H2>
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The
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<I>/proc/ioports</I>
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file shows the I/O ports that are currently allocated on the system.
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<P>
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Before Linux 2.4,
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permissions were not inherited by a child created by
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<B><A HREF="/cgi-bin/man/man2html?2+fork">fork</A></B>(2).
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<P>
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Glibc has an
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<B>ioperm</B>()
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prototype both in
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<I><<A HREF="file:///usr/include/sys/io.h">sys/io.h</A>></I>
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and in
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<I><<A HREF="file:///usr/include/sys/perm.h">sys/perm.h</A>></I>.
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Avoid the latter, it is available on i386 only.
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<A NAME="lbAI"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?2+iopl">iopl</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+outb">outb</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?7+capabilities">capabilities</A></B>(7)
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<A NAME="lbAJ"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="5"><A HREF="#lbAB">NAME</A><DD>
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<DT id="6"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="7"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="8"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="9"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="10"><A HREF="#lbAG">CONFORMING TO</A><DD>
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<DT id="11"><A HREF="#lbAH">NOTES</A><DD>
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<DT id="12"><A HREF="#lbAI">SEE ALSO</A><DD>
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<DT id="13"><A HREF="#lbAJ">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:33 GMT, March 31, 2021
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</BODY>
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</HTML>
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