iopl - 改變I / O權限級彆

內容簡介

#include <sys/io.h>

int iopl(int level);

描述

iopl() 改變當前進程的I/ O特權級彆，在級彆 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的優先級為0。

這個調用主要是為i386體係結構。在許多其它體係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

標簽	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)