X86_64_IOPL(2) BSD/x86_64 System Calls Manual X86_64_IOPL(2)NAME
x86_64_iopl -- change the x86_64 I/O privilege level
LIBRARY
x86_64 Architecture Library (libx86_64, -lx86_64)
SYNOPSIS
#include <sys/types.h>
#include <machine/sysarch.h>
int
x86_64_iopl(int iopl);
DESCRIPTION
x86_64_iopl() sets the x86_64 I/O privilege level to the value specified by iopl. This call is restricted to the super-user.
RETURN VALUES
Upon successful completion, x86_64_iopl() returns 0. Otherwise, a value of -1 is returned and the global variable errno is set to indicate
the error.
ERRORS
x86_64_iopl() will fail if:
[EPERM] The caller was not the super-user, or the operation was not permitted at the current security level.
WARNING
You can really hose your machine if you enable user-level I/O and write to hardware ports without care.
BSD July 3, 2002 BSD
Check Out this Related Man Page
IOPL(2) Linux Programmer's Manual IOPL(2)NAME
iopl - change I/O privilege level
SYNOPSIS
#include <sys/io.h>
int iopl(int level);
DESCRIPTION
iopl changes the I/O privilege level of the current process, as specified in level.
This call is necessary to allow 8514-compatible X servers to run under Linux. Since these X servers require access to all 65536 I/O ports,
the ioperm call is not sufficient.
In addition to granting unrestricted I/O port access, running at a higher I/O privilege level also allows the process to disable inter-
rupts. This will probably crash the system, and is not recommended.
Permissions are inherited by fork and exec.
The I/O privilege level for a normal process is 0.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
ERRORS
EINVAL level is greater than 3.
EPERM The current user is not the super-user.
CONFORMING TO
iopl is Linux specific and should not be used in processes intended to be portable.
NOTES
Libc5 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.
SEE ALSO ioperm(2)Linux 0.99.11 1993-07-24 IOPL(2)
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