Core Architecture
Available a complete operating system mainly consists of four parts: hardware, operating system kernel, operating system services, user applications.
linux kernel main purpose is to interact with the computer hardware and programming interfaces to control the hardware operation, scheduling access to hardware resources, to provide an advanced virtual execution environment and hardware interface for the user program.
The operating system kernel mode structure can be divided into: a monolithic single-core mode and the hierarchical model of the microkernel, linux0.11 single mode core, the single-core mode main advantage is a compact structure of the kernel code, execution speed, deficiencies mainly at the structural level is not strong.
Process operating system provides services single kernel mode:
the application specified parameter values system call instruction (int 0x80), causing the CPU to switch from user mode to kernel mode
operating system then invokes a particular system call according to the specific parameter values service program
the service program is to make a call in accordance with some of the underlying support function to perform a specific function
after the completion of the service required by the application, the operating system allows the CPU to switch back from kernel mode to user mode application returns
the single kernel mode:
- The main program calls the service layer
- Service layer performs system calls
- Functions supported by the underlying system calls
System kernel module
linux kernel is divided into five modules:
- Process Scheduling Module: used to process responsible for controlling the use of CPU resources.
- Memory Management Module: to ensure that all processes can be safely shared memory area, the process virtual memory also uses more memory space than the actual memory capacity and memory using a file system to exchange data.
- File system module: support for external drives and storage devices, virtual file system provides a versatile file interface through to all external storage devices, hides the details of the various different hardware devices.
- Interprocess communication module: to support information exchange between multiple processes.
- Network interface module: to provide access to a variety of network communication standards and supports many network hardware.
FIG kernel module structure and dependencies:
the core structure:
