When dealing with such complex systems such as the software package of a smart mobile phone, it is necessary to apply powerful methods to detect and report errors when they occur. This paper probes and analyzes a powerful debug method called trap and exception handling, which is supported by the ARM platforms. The method can easily capture some valuable debug information. When a fatal error occurs during runtime or system detects an abnormal, a trap or an exception shall be logged and stored in the non-volatile random access memory (NVRAM). The information must be enough and easy for engineer to analyze the software error.