ioperm - set port input/output permissions
#include <sys/io.h> /* for glibc */
int ioperm(unsigned long
from, unsigned long
ioperm() sets the port access permission bits for the calling thread for
num bits starting from port address
turn_on is nonzero, then permission for the specified bits is enabled; otherwise it is disabled. 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.
This call is mostly for the i386 architecture. On many other architectures it does not exist or will always return an error.
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.
This page is part of release 4.15 of the Linux
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