ioperm(2) -- Linux man page
NAMEioperm - set port input/output permissions
SYNOPSIS#include <unistd.h> /* for libc5 */
#include <sys/io.h> /* for glibc */
DESCRIPTIONIoperm 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 inherited on fork, but on exec they are. This is useful for giving port access permissions to non-privileged tasks.
RETURN VALUEOn success, zero is returned. On error, -1 is returned, and errno is set appropriately.
- Invalid values for from or num.
- Caller does not have the CAP_SYS_RAWIO privileges.
- (on ppc) This call is not supported.
CONFORMING TOioperm is Linux specific and should not be used in programs intended to be portable.
NOTESLibc5 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.