Deep Dive into the Arch of Linux 4 Kernel
Linux, the open-source operating system, has been around for several decades and is constantly evolving. One of the key elements that make Linux such a flexible and versatile platform is its kernel. The Linux kernel is the central component responsible for managing system resources and Providing access to hardware Devices. In this article, we will take a deep dive into the architecture of the Linux 4 kernel and explore how it works.
Overview of Linux 4 Kernel Architecture
The Linux 4 kernel is divided into several layers, each with its own responsibilities. The lowest layer is the hardware layer, which interacts with the physical hardware components such as the CPU, memory, and I/O controllers. Above the hardware layer is the kernel space, which contns the core components of the kernel, such as the process scheduler, memory manager, and device driver interface. These components work together to manage system resources and provide access to hardware devices.
Beyond the kernel space is the user space, which contns all the applications and user-level processes running on the system. The kernel space and user space are separated by a system call interface, which allows user-level processes to interact with kernel-level services.
The architecture of the Linux 4 kernel is based on a modular design, with each component designed to function independently. This allows for easy customization and modification of the kernel to suit specific hardware platforms or user requirements.
Process Management
The Linux 4 kernel’s process management component is responsible for managing the execution of running processes on the system. This involves managing process states, allocating and managing resources such as CPU time and memory, and scheng processes for execution.
The process scheduler in the Linux 4 kernel uses a priority-based algorithm to determine which process is scheduled for execution next. This ensures that high-priority processes receive preferential treatment, and lower-priority processes are only executed when sufficient resources are avlable.
Memory Management
The memory management component in the Linux 4 kernel is responsible for managing system memory usage. This involves allocating and deallocating memory to running processes, managing memory usage at the system level, and providing virtual memory support.
The memory management component in Linux 4 provides support for dynamic memory allocation, which allows a process to request memory at run-time. This component also includes support for virtual memory, which allows the system to use disk space as additional memory when the physical memory is exhausted.
Device Management
Linux 4 kernel provides support for a wide range of hardware devices. The device management component in the kernel is responsible for interfacing with hardware devices and providing access to these devices for user-level processes.
The device management component in Linux 4 uses a modular approach, with device drivers designed to function as individual modules. This approach allows for easy customization of the kernel to include support for new or legacy hardware devices.
Networking
Networking support in the Linux 4 kernel includes support for standard networking protocols such as TCP/IP and UDP, as well as support for advanced networking protocols such as IPv6 and IPsec.
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如何安装ArchLinux
1首先你要拥有一个U盘作为驱动。 U盘安装archlinux并不能像ubuntu用iso软件直接将iso文件写入U盘。 稍有不用，这里向你推荐使用dd方法，过程简单，仅需一句代码。 2开机选择U盘驱动，方法因不同机器而不同，这里不再详细介绍。 3进入选择列表，根据你的选择进入安装。 4开始真正的安装前，必须检测网络是否连接。 因为安装必须联网进行下载。 输入ping 如果网络连接失败，应连接成功，否则安装无法进行。 5输入 lsblk查看硬件设备。 sda是电脑硬盘。 输入：fdisk /dev/sda 进行分区。 输入4 /dev/sda1. 这个过程是格式化。 为了方便仅分一个区，具体分区方法可自定义。 格式化后，将分区挂载到/mnt上输入： mount /dev/sda1 /mnt现在修改源。 输入：vi /etc/pacman.d/mirrorslist将不是中国的源删除，快捷键dd。 同时建议将163的源剪切只第一行。 快捷键dd删除，然后p就可以实现粘贴。 现在可以进行安装了。 输入：pacstrap /mnt base安装完毕后。 输入：arch-chroot /mnt此时安装grub。 输入：pacman -S grub安装配置grub输入：grub-install /dev/sda最后配置boot文件。 输入：grub-mkconfig -o /boot/grub/了，输入exit退出，再输入reboot重启。 一切都安装好了。
如何给linux安装新内核
清除垃圾（这一步：一般是在就内核重新编译时使用，在编译新的内核是不需要）；make clean及make mrproper；进行内核裁减配置；内核裁减配置的原则：从实际出发。 如：根据支持的硬件设备来决定需要选择的驱动模块，根据需要选择所支持的文件系统格式等；具体配置命令为：make config ：通过命令接口，依次要求你设定每个选项，如果文件存在，会根据该文件来设置默认值；make menuconfig ：显示以curses为基础的、终端式的配置菜单。 makexconfig ：图形界面，显示以Tk为基础X Window配置菜单。 最常用的为：make menuconfig（注：需要ncurses的rpm包）。 说明：这一步中选择为M模式的，编译到/lib/modules/下相关目录文件中；选择为*模式的，编译到内核中即/boot/vmlinuz中，启动时加载到内核中。 具体内核裁减配置参阅其它资料。 第四步：生成依赖关系（make dep）内核源码树中大多数文件都会与一些头文件有依存关系，要想编译内核顺利，在正式编译前必须让内核源码树中的各个Makefile文件知道这些依存关系。 依存关系建立期间会在内核源码树中每个子目录里产生一个隐藏的文件，此文件内含子目录里各个文件所依存的头文件清单。 第五步：建立内核映像和模块2.4内核：make bzImage：在arch/YOUR_ARCH/boot/中生成在在zImage内核映像文件；make modules：在相应目录下生成内核模块（即驱动模块）2.6内核：make：作用相当于make bzImage与make modules第六步：安装模块（make modules_install）让make modules或make 过程中产生的.o驱动模块拷入/lib/modules/下相应目录中；第七步：安装内核第一种情况：直接使用make install命令即可。 第二中情况：先采用cp arch/i386/boot/bzImage /boot/×××（×××表示自己随意的命名）mkinitrd /boot/××× 2.6.12.6（内核版本号）
Linux内核中等待队列的几种用法
1. 睡眠等待某个条件发生(条件为假时睡眠)：睡眠方式：wait_event, wait_event_interruptible唤醒方式：wake_up (唤醒时要检测条件是否为真，如果还为假则继续睡眠，唤醒前一定要把条件变为真)2. 手工休眠方式一：1)建立并初始化一个等待队列项DEFINE_WAIT(my_wait) <== wait_queue_t my_wait; init_wait(&my_wait);2)将等待队列项添加到等待队列头中，并设置进程的状态prepare_to_wait(wait_queue_head_t *queue, wait_queue_t *wait, int state)3)调用schedule()，告诉内核调度别的进程运行4)schedule返回，完成后续清理工作finish_wait()3. 手工休眠方式二：1)建立并初始化一个等待队列项：DEFINE_WAIT(my_wait) <== wait_queue_t my_wait; init_wait(&my_wait);2)将等待队列项添加到等待队列头中：add_wait_queue3)设置进程状态__set_current_status(TASK_INTERRUPTIBLE);4)schedule()5)将等待队列项从等待队列中移除remove_wait_queue()其实，这种休眠方式相当于把手工休眠方式一中的第二步prepare_to_wait拆成两步做了，即prepare_to_wait <====add_wait_queue + __set_current_status，其他都是一样的。4. 老版本的睡眠函数sleep_on(wait_queue_head_t *queue)：
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