ioperm

IOPERM(2)                  Linux Programmer's Manual                 IOPERM(2)



NAME
       ioperm - set port input/output permissions

SYNOPSIS
       #include <unistd.h> /* for libc5 */
       #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 process for num
       bytes starting from port address from to the value turn_on.  The use of
       ioperm requires root privileges.

       Only  the  first  0x3ff I/O ports can be specified in this manner.  For
       more ports, the iopl function must be used.  Permissions are not inher-
       ited  on  fork,  but  on  exec they are. This is useful for giving port
       access permissions to non-privileged tasks.

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

CONFORMING TO
       ioperm is Linux specific and should not be used in programs intended to
       be portable.

NOTES
       Libc5 treats it as a system call and has  a  prototype  in  <unistd.h>.
       Glibc1  does  not  have  a  prototype.  Glibc2  has a prototype both in
       <sys/io.h> and in <sys/perm.h>.  Avoid the latter, it is  available  on
       i386 only.

SEE ALSO
       iopl(2)



Linux                             1993-01-21                         IOPERM(2)