Porting And Test Of Real-time Embedded Linux Kernel RTAI

Among main open source softwares, Linux is quickly entering the real-time control field with open kernel source codes, stable performance, UNIX compatibility, multiple processes applicability, great network capabilities, high security and pruned kernel. Due to it's non-preemptive kernel, coarse time granularity, frequently interrupt disable, virtual memory, process scheduling mechanism and other buffer mechanism, Linux is not so"real-time"as an RTOS.Using the real-time kernel RTAI and Linux kernel, we completed the porting of real-time kernel to a specific hardware platform—S3C2410 platform, and got a real-time Linux. Porting was completed mainly from the following aspects: First, implementing the control of the interruption. Using an interrupt simulator to take over all the disruption, the Linux can not mask the hardware interruption , thus enabling real-time tasks and real-time interrupt rapid response. Different methods were taken by the RTAI due to different microprocessor platform, so we used the method of interrupt control for the S3C2410 microprocessor to achieve RTAI's control for the underlying hardware. This was followed by the porting of system clock. RTAI makes the system clock more refined granularity by setting one-shot mode timer to make the clock interrupt happen on needed time. We used a number of hardware clocks to achieve the respective one-shot mode mode clock and the periodic mode, completing the porting of system clock. Furthermore, we made use of the MMU,Cache,memory management supported by S3C2410 to realize a dynamic memory management module.A real-time ability test was carried through based on the embedded system. Interrupt latency and task switch time were chosen to measure the real-time response capability of Linux before and after it be realtimed.