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    The following form allows you to view linux man pages.

    Command:

    ioperm

    
    
    

    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 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 dis-
           abled.  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 not inherited by the child created by fork(2);  follow-
           ing  a  fork(2) the child must turn on those permissions that it needs.
           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 architec-
           tures 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.
    
           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.
    
    
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