Linux内核有主要功能吗?

问题描述

我正在学习Device Driver和Kernel编程.根据Jonathan Corbet的书，我们在设备驱动程序中没有main()功能.

I am learning Device Driver and Kernel programming.According to Jonathan Corbet book we do not have main() function in device drivers.

#include <linux/init.h>
#include <linux/module.h>

static int my_init(void)
{
     return  0;
}

static void my_exit(void)
{
     return;
}

module_init(my_init);
module_exit(my_exit);

这里我有两个问题:

1. 为什么我们在设备驱动程序中不需要main()功能?
2. 内核是否具有main()功能?

1. Why we do not need main() function in Device Drivers?
2. Does Kernel have main() function?

推荐答案

从根本上讲，将例程命名为main()并没有什么特别的.如上所述，main()用作可执行加载模块的入口点.但是，您可以为装入模块定义不同的入口点.实际上，您可以定义多个入口点，例如，引用您喜欢的dll.

Fundamentally, there is nothing special about a routine being named main(). As alluded to above, main() serves as the entry point for an executable load module. However, you can define different entry points for a load module. In fact, you can define more than one entry point, for example, refer to your favorite dll.

从操作系统(OS)的角度来看，它真正需要的只是充当设备驱动程序的代码的入口点的地址.当需要设备驱动程序对设备执行I/O操作时，操作系统会将控制权传递给该入口点.

From the operating system's (OS) point of view, all it really needs is the address of the entry point of the code that will function as a device driver. The OS will pass control to that entry point when the device driver is required to perform I/O to the device.

系统程序员定义(每个OS都有自己的方法)设备之间的连接，充当设备驱动程序的加载模块以及加载模块中入口点的名称.

A system programmer defines (each OS has its own method) the connection between a device, a load module that functions as the device's driver, and the name of the entry point in the load module.

每个操作系统(显然)都有自己的内核，有些可能(也许)以main()开头，但是我发现使用了main()的内核而不是简单的内核(例如UNIX)使我感到惊讶.在编写内核代码时，您已经远远超出了将要编写的每个模块命名为main()的要求.

Each OS has its own kernel (obviously) and some might/maybe start with main() but I would be surprised to find a kernel that used main() other than in a simple one, such as UNIX! By the time you are writing kernel code you have long moved past the requirement to name every module you write as main().

希望这有帮助吗?

从Unix版本6的内核中找到此代码段.如您所见，main()只是另一个程序，正在尝试入门！

Found this code snippet from the kernel for Unix Version 6. As you can see main() is just another program, trying to get started!

main()
{
     extern schar;
     register i, *p;
     /*
     * zero and free all of core
     */

     updlock = 0;
     i = *ka6 + USIZE;
     UISD->r[0] = 077406;
     for(;;) {
        if(fuibyte(0) < 0) break;
        clearsig(i);
        maxmem++;
        mfree(coremap, 1, i);
         i++;
     }
     if(cputype == 70)
     for(i=0; i<62; i=+2) {
       UBMAP->r[i] = i<<12;
       UBMAP->r[i+1] = 0;
      }

    // etc. etc. etc.

这篇关于Linux内核有主要功能吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！