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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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ioperm(2) System Calls Manual ioperm(2)
ioperm - set port input/output permissions
Standard C library (libc, -lc)
#include <sys/io.h>
int ioperm(unsigned long from, unsigned long num, int turn_on);
ioperm() sets the port access permission bits for the calling
thread for num bits starting from port address from. If 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.
Permissions are inherited by the child created by fork(2) (but
see NOTES). Permissions are preserved across execve(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.
On success, zero is returned. On error, -1 is returned, and
errno is set to indicate the error.
EINVAL Invalid values for from or num.
EIO (on PowerPC) This call is not supported.
ENOMEM Out of memory.
EPERM The calling thread has insufficient privilege.
glibc has an ioperm() prototype both in <sys/io.h> and in
<sys/perm.h>. Avoid the latter, it is available on i386 only.
Linux.
Before Linux 2.4, permissions were not inherited by a child
created by fork(2).
The /proc/ioports file shows the I/O ports that are currently
allocated on the system.
iopl(2), outb(2), capabilities(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
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⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.9.1 2024-05-02 ioperm(2)
Pages that refer to this page: fork(2), ioctl_console(2), iopl(2), outb(2), syscalls(2), unimplemented(2), mem(4), systemd.exec(5), capabilities(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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