Free Knowledge Resources


Linux Manual Pages


Free Software * Books

Source Code

Free Media

Linux

ioperm(2)


NAME

   ioperm - set port input/output permissions

SYNOPSIS

   #include <sys/io.h> /* for glibc */

   int ioperm(unsigned long from, unsigned long num, int turn_on);

DESCRIPTION

   ioperm()  sets  the  port access permission bits for the calling thread
   for num bits starting from port address from.  If turn_on  is  nonzero,
   then  permission  for  the  specified  bits is enabled; otherwise it is
   disabled.  If turn_on is nonzero, the calling thread must be privileged
   (CAP_SYS_RAWIO).

   Before  Linux  2.6.8, only the first 0x3ff I/O ports could be specified
   in this manner.  For more ports, the iopl(2) system call had to be used
   (with  a level argument of 3).  Since Linux 2.6.8, 65,536 I/O ports can
   be specified.

   Permissions are inherited by the child  created  by  fork(2)  (but  see
   NOTES).  Permissions are preserved across execve(2); this is useful for
   giving port access permissions to unprivileged programs.

   This  call  is  mostly  for  the  i386  architecture.   On  many  other
   architectures it does not exist or will always return an error.

RETURN VALUE

   On  success,  zero is returned.  On error, -1 is returned, and errno is
   set appropriately.

ERRORS

   EINVAL Invalid values for from or num.

   EIO    (on PowerPC) This call is not supported.

   ENOMEM Out of memory.

   EPERM  The calling thread has insufficient privilege.

CONFORMING TO

   ioperm() is Linux-specific and should not be used in programs  intended
   to be portable.

NOTES

   The /proc/ioports file shows the I/O ports that are currently allocated
   on the system.

   Before Linux 2.4, permissions were not inherited by a child created  by
   fork(2).

   Glibc has an ioperm() prototype both in <sys/io.h> and in <sys/perm.h>.
   Avoid the latter, it is available on i386 only.

SEE ALSO

   iopl(2), outb(2), capabilities(7)

COLOPHON

   This page is part of release 4.09 of the Linux  man-pages  project.   A
   description  of  the project, information about reporting bugs, and the
   latest    version    of    this    page,    can     be     found     at
   https://www.kernel.org/doc/man-pages/.



Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.



Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.



Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.



Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.


birds banner