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Binary Decomposition PrincipleAny positive integer can be decomposed into a sum of distinct powers of two (2n, where n ≥ 0). This mathematical property, which forms the foundation of binary representation, is the core mechanism leveraged by the Buddy allocation system.Kernel Buddy System Data Structure HierarchyThe architecture of the Buddy sys ...

eventfd(2) Combined with seelect(2) Source Code Analysis The code examples are from Linux kernel 4.17 eventfd(2) - Creates a file descriptor for event notification. Usage Source Code Analysis References #include <sys/eventfd.h> int eventfd(unsigned int initval, int flags); int eventfd2(unsigned int initval, int flags); Parameters - \ ...

Understanding the Platform Bus The platform bus is a virtual bus within the Linux kernel architecture, designed to unify the device and driver model. Unlike physical buses such as PCI or USB, the platform bus does not correspond to any physical hardware. It exists to manage devices that do not naturally fit into other bus models, ensuring a con ...

This analysis is based on Linux kernel 4.19.195. Software Implementation Principles The RCU implementation in software revolves around idnetifying the beginning of a Grace Period (GP), detecting Quiescent States (QS), determining when a grace period ends, handling post-grace-period cleanup, and initiating the next grace period—a large state mac ...

Character Device Driver Foundations Developing a Linux character device driver generally follows a standard sequence of operations: Acquire a major device number, either statically assigned or dynamically allocated by the kernel. Declare a file_operations structure to define the driver's supported interactions. Implement the requisite handlers ...

Using Linux kernel version 4.19.291 as the reference base. ARM Architecture System Call Table The system call definitions for ARM are located in the source file: linux-4.19.291/arch/arm/tools/syscall.tbl File Format Structure Each line in the table represents a specific system call entry with the following syntax: <id> <abi_type> ...

The Core of USB Redirection USB redirection makes a physical device attached to one host accessible to another host over a network, as if it were locally connected. The goal is not to share files or relay a high-level protocol, but to forward USB bus-level requests and responses between two machines. On Linux, usbip is the reference implementat ...

Virtual IP Configuration virtual_ipaddress { 10.0.0.3/24 dev eth0 label eth0:1 } track_script { health_check } Failover Testing [root@lb01 ~]# systemctl is-active nginx active [root@lb01 ~]# ip a | grep 0.3 inet 10.0.0.3/24 scope global secondary eth0:1 [root@lb01 ~]# systemctl stop nginx [root@lb01 ~]# ip a | grep 0.3 # VIP migrated after ...

Overview Mutexes (mutual exclusion locks) are synchronization primitives provided by the Linux kernel to hendle concurrent accesss to shared resources. Unlike semaphores which allow multiple concurrent access, a mutex ensures that only one thread can hold the lock at any given time. This article demonstrates how to integrate mutex synchronizati ...