ioperm - set port input/output permissions
int ioperm(unsigned long from, unsigned long num, int
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 inherited on fork, but on exec they are.
This is useful for giving port access permissions to non-
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
ioperm is Linux specific and should not be used in programs
intended to be portable.