The Research Of Remote Debugging Technology Based On Embedded Real-time Operating System

With the rapid development of computer hardware, resources of embedded system processor have been greatly optimized, making people require more about it. Although the scale of software is becoming increasingly larger, the cycle of its development is getting shorter. The difficulties of embedded software development lie in the post-commissioning process. Studies have shown that the debugging time occupies more than50%of the entire embedded software development time. Therefore, good debugging methods and tools are significant to embedded software development.Compared with general-purpose computer, embedded system hardware resources are still limited. They usually can’t independently complete the local debugging, and need the help of the resource-rich general purpose computer to complete tasks. That is to say, embedded software debugging commonly uses the method of remote debugging. Current debugging methods include:insert stub debugging method、 on-chip debugging method and pure software simulation debugging method. However, these methods still have some defects. For example, current insert stub debugging method generates debugging interruption by inserting the exception instructions that needs to frequent changes for the programs being debugged. Not only does this method violate the debugging Heisnberg principle, but also it does not apply to the embedded systems whose programs run directly in Flash. Also, this method may cause the priority inversion in debugging process, reducing the real time performance of debugging system and the whole embedded system. On-chip debugging method requires hardware to pause during the debugging process. Thus, it is not suitable for the debugging of embedded software which responses to the time sensitivity. And pure software simulation debugging method is very difficult to debug the routines related to input and output.Considering the problems above, this paper presents a debugging method that doesn’t interrupt the hardware implementation, and uses the timer to generate debugging interruption and to be able to keep the real-time debugging state. Firstly, we analyze several current debugging methods. Secondly, we present a debugging model, illustrate the debug interrupt generation in detail, and design some data structures to save the debugging state. And then we put forward a peripheral device management method that is used to restrain the priority inversion in the debugging process, and give it theoretical analysis. Finally, we design a debugger specifically according to the proposed debugging method and describe it concretely from the following aspects:debugging function of debugger, communication protocol between the host and target, and the processing of debugging commands.