ioperm - phpMan

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 priv-
       ileges.

       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 inherited on fork, but on exec
       they  are.  This  is  useful  for  giving port access permissions to non-privileged
       tasks.

       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 appropri-
       ately.

ERRORS
       EINVAL Invalid values for from or num.

       EPERM  Caller does not have the CAP_SYS_RAWIO privileges.

       EIO    (on ppc) This call is not supported.

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)

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