| As the rapid development of information technology and microelectronics, embedded systems are widely used in industrial production control, smart instrumentation, defense technology, information appliances, network communication. As an important part of embedded systems, operating system is studied by more and more people. In all kinds of existing operating systems, Linux operating system is widely used in embedded system because of its powerful function, clear structure, open source. The volume of the common linux operating system is big and its function is complete. In the embedded system, the resource is limited, the requirements for the volume of the software is relatively high, the function of the system is also more specific. The file size of the common Linux operating system is large and its function is complete. So, it must be cut. The cutting technology for linux operating system is also currently one of the hot research areas in computer field.The popular Linux cutting technology and its advantages and disadvantages are analyzed in this paper, the cutting method based on call graph is selective analyzed, the dependent relation between functions is found out by hand drawing the call graph between functions, the granularity of this kinds of cutting method is small, but when the code of application program is comparatively large, it is troublesome to construct the call graph of functions, and it is easy to neglect the functions that have been called. For this problem, based on the cutting idea of call graph, the linux fine granularity cutting method based on application program is proposed, firstly, a program for analyzing functions is writed to quickly find out the library functions that have been called in the application program, then the call relation between functions is analyzed, at last, according to Corresponding relation between library functions and kernel functions, the kernel functions that have been called in the application program is found out. The library functions and kernel functions that haven't been used are cutted, in order to archieve the fine granularity cutting.Finally, the operating system based on video sample system is designed, introduces the concrete process of cutting the operating system, in the first step, the configuration tool of linux is used to coarse granularity cutting; in the second step, the fine granularity cutting method based on application program is used to fine granularity cutting, including the cutting for library functions and library functions. The operating system after cutting is downloaded to the Samsung's Micro2440 development board, and it runs well, meet the functional requirements of the video sample. |
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