Seed: an Embedded Real-Time Operating System for Network Appliances

Abstract

Traditional embedded operating systems usually address two issues: limited hardware resources and real-time support. However, due to the popularity of Internet and rapid development of network technologies, Internet access capability is also becoming a necessarily for many embedded systems. As a result, modern embedded operating systems should satisfy the requirements of running on top of limited hardware resources, supporting real-time applications, and providing Internet access capability. Many commercial real-time operating systems do satisfy the above requirements. However, they are usually expensive and not open source. On the other hand, non-commercial kernels often have limitations for fulfilling the requirements. This motivates us to develop an open source, embedded real-time operating system with Internet access capability. The kernel is named Seed. It is small, flexible, and portable. And, the kernel services have deterministic or even constant timing behavior so that it can satisfy the real-time needs. Finally, it enables Internet access by integrating a tiny and open source TCP/IP protocol stack, lwIP. Seed is currently run on top of the Samsung SNDS100 (ARM7TDMI based) evaluation board. The size of the kernel image is about 75K bytes with lwIP, or 21K bytes without lwIP. According to the performance results, Seed is suitable for real-time embedded network appliances.