Porting And Tailoring Real-Time Linux Based On Loongson 1E

With the rapid development of China's aerospace industry in recent years,the field of satellite applications has been continuously expanded,and the software functions of satellites have become more and more complex.It is an inevitable trend to use the operating system to manage the on-board missions and on-board payloads.The emergence of the domestic Loongson 1E processor,with its high performance and low power consumption,has broken the blockade of foreign space chips in China.In this context,it is of great significance to study the transplantation of embedded real-time Linux system based on Godson platform.Based on the analysis of embedded operating systems at home and abroad,this paper studies the real-time method of standard Linux kernel,analyzes the feasibility of porting real-time Linux to Loongson 1E platform,and designs and improves the Linux system based on the particularity of aerospace projects.The exception handling strategy,tailoring the kernel according to the needs of the space mission,and finally testing the real-time performance of the platform.The main work of this paper is to design and build an embedded real-time operating system platform based on Godson processor,and to explore the application research of embedded real-time operating system based on MIPS architecture processor in domestic aerospace field.The main research contents of this paper include:(1)On the basis of detailed investigation of common real-time operating systems, compare and analyze their characteristics,and choose RT-Preempt patch for real-time improvement of Linux.At the same time,the principle of RT-Preempt patch interrupt threading,critical section preemption,high-precision clock, real-time scheduling strategy,priority inheritance and so on are analyzed.(2)Based on the analysis of the BootLoader boot process and the Linux system boot mode under the MIPS architecture,BootLoader boot Linux kernel boot; successfully transplant the RT-Preempt patch Linux kernel and complete the root file system creation;Special requirements for reliability,design and improvement of the MIPS architecture operating system exception handling mechanism.(3)In view of the tight resource of embedded system,based on the analysis of the modular design mechanism of Linux kernel,the kernel is tailored at the module level,function level and code level through three different granularity cutting methods.(4)Complete the key real-time performance index test of the operating system after transplant cutting,including: platform context switching time,interrupt response and recovery time;use the professional real-time testing tool Cyclictest to test the platform and summarize the test results.Finally,the experimental test shows that RT-Preempt patch can effectively improve the real-time performance of standard Linux.The embedded real-time Linux platform based on Godson processor can meet the real-time requirements of the aerospace project.