Transplant Of1wIP Protocol Based On UIO Framework

In the safety-critical area, if an application relays on the Linux kernel network stack, the entire Linux kernel network stack has to be certificated, because it is not isolated in any way. Since the network subsystem is one of the largest kernel components, its complexity makes the verification work very difficult or arguably impossible. However, in practice, we often only need the simple receive and transmit operations.In this work, we implemented a user space NIC driver based on the UIO(user space IO) framework of the Linux kernel. The driver can bypass the Linux kernel network stack, but also meet our requirement. We also ported a light weight TCP/IP stack lwIP (light weight IP) to replace the original in kernel network stack. This will greatly simplify our safety certification work. Meanwhile, there are the other advantages. Errors of the userspace driver will never crash the kernel and the maintenance of the userspace driver is easier than the in-kernel one, for example.The performance testing data shows that the userspace NIC driver’s performance is slightly worse than the native in kernel one. The reason is that the userspace NIC driver introduces extra interruption delay and context switches. But, the userspace NIC driver still meets our requirements.