iopl - 改變I / O權限級別

內容簡介

#include <sys/io.h>

int iopl(int level**);**

描述

iopl () 改變當前進程的I/ O特權級別，在級別  level 指定。 .

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 interrupts. This will probably crash the system, and is not recommended.

Permissions are inherited by fork() and exec().

對於一個正常的過程I / O的優先級爲0。

這個調用主要是爲i386體系結構。在許多其它體系結構不存在或將總是返回一個錯誤。

返回值

On success, zero is returned. On error, -1 is returned, and  errno  is set appropriately.

錯誤

標籤

描述

EINVAL

level is greater than 3.

ENOSYS

This call is unimplemented.

EPERM

The calling process has insufficient privilege to call iopl(); theCAP_SYS_RAWIO capability is required.

遵循於

iopl () is Linux specific and should not be used in processes intended to be portable.

注意

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.

另請參閱

• ioperm (2)