The Linux kernel is the core part of the operating system, responsible for managing computer hardware resources and providing system services. The working principle of the Linux kernel can be divided into the following aspects:
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Process management: The Linux kernel implements multitasking through process management. It is responsible for creating, scheduling, and terminating processes, and provides inter-process communication mechanisms such as signals, pipes, shared memory, and more. The kernel uses a scheduling algorithm to determine which process to execute when, and allocates time slices for each process to achieve concurrent execution.
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Memory management: The Linux kernel manages the physical memory and virtual memory of the system. It is responsible for mapping the virtual address of the process to physical memory, and handles memory allocation, deallocation, and swapping. The kernel also manages access rights to virtual memory through page tables and uses page replacement algorithms to optimize memory usage.
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File system: The Linux kernel provides a file system interface that enables users to read and write files and directories. It organizes files and directories into a hierarchy and provides operations on files such as opening, closing, reading, writing, and deleting. The kernel interacts with the storage device through the file system driver, stores the file data on the disk, and maintains the metadata information of the file.
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Device Drivers: The Linux kernel manages the computer's hardware devices through device drivers. It provides an interface to communicate with the device and handles initialization, configuration and control of the device. The kernel abstracts devices into character devices, block devices, and network devices, and interacts with them through corresponding drivers.
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System calls: The Linux kernel provides system services to user space programs through system calls. A system call is an interface between a user program and the kernel, and is used to request the kernel to perform privileged operations, such as file operations, process management, and network communication. The kernel provides a set of system calls to realize these functions, and provides corresponding function libraries for user programs to call.
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Interrupt handling: The Linux kernel responds to hardware events and exceptions through interrupt handling. When a hardware device is interrupted, the kernel will call the corresponding interrupt handler according to the interrupt number of the device. The interrupt handler is responsible for saving the current context, handling interrupt events, and waking up related processes for processing as needed.
Overall, the Linux kernel is organized in a modular manner, and provides system functions and manages hardware resources through mechanisms such as system calls, interrupt handling, and device drivers. It runs silently in the background, providing a stable and efficient execution environment for user programs and applications.