内容简介
#include <sys/io.h>int iopl(int level);
描述
iopl() 改变当前进程的I/ O特权级别，在级别 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().
对于一个正常的过程I / O的优先级为0。
这个调用主要是为i386体系结构。在许多其它体系结构不存在或将总是返回一个错误。
返回值
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.错误
| 标签 | 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. |
遵循于
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.另请参阅
