|| Linux Programmer's Manual
NAME ioperm - set port input/output permissions
/* for libc5 */
/* for glibc */
int ioperm(unsigned long
, unsigned long
() sets the port access permission bits for the calling thread for
bits starting from port address
is nonzero, then permission for the specified bits is enabled; otherwise it is disabled. If
is nonzero, the calling thread must be privileged (
Before Linux 2.6.8, only the first 0x3ff I/O ports could be specified in this manner. For more ports, the
(2) system call had to be used (with a
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
(2); following a
(2) the child must turn on those permissions that it needs. Permissions are preserved across
(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.
Invalid values for
(on PowerPC) This call is not supported.
Out of memory.
The calling thread has insufficient privilege.
ioperm() is Linux-specific and should not be used in programs intended to be portable.
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
. Glibc1 does not have a prototype. Glibc2 has a prototype both in
. Avoid the latter, it is available on i386 only.
COLOPHON This page is part of release 3.53 of the Linux
man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.