linux 内核上下文中的硬件 "gates" 是什么？
What are hardware "gates" in the context of the linux kernel?
In user space, the ioctl system call has the following prototype:
int ioctl(int fd, unsigned long cmd, ...);
The prototype stands out in the list of Unix system calls because of the dots, which usually mark the function as having a variable number ofarguments. In a real system, however, a system call cannot actually have a variable number of arguments. System calls must have a well-defined prototype, because user programs can access them only through hardware "gates".
那么这些硬件门是什么？页码为 135 和 136。
硬件"gates" 是允许切换到内核上下文的特定指令，通常是让程序向内核请求某些东西。这可能是 syscall、sysenter 或 int 0x80 之类的指令，具体取决于您的系统。
我应该注意，这些在实践中通常不称为 "hardware gates"，而是类似于 "system calls instructions."
In user space, the ioctl system call has the following prototype:
int ioctl(int fd, unsigned long cmd, ...);The prototype stands out in the list of Unix system calls because of the dots, which usually mark the function as having a variable number ofarguments. In a real system, however, a system call cannot actually have a variable number of arguments. System calls must have a well-defined prototype, because user programs can access them only through hardware "gates".
那么这些硬件门是什么？页码为 135 和 136。
硬件"gates" 是允许切换到内核上下文的特定指令，通常是让程序向内核请求某些东西。这可能是 syscall、sysenter 或 int 0x80 之类的指令，具体取决于您的系统。
我应该注意，这些在实践中通常不称为 "hardware gates"，而是类似于 "system calls instructions."