This paper presents a novel flexible, dependable, and reliable operating system design for distributed reconfigurable system on chip. The dependability and reliability are achieved by integrating online model checking technique. Each OS service has different implementations which are further partitioned into small blocks. This operating system design allows the OS service to be adapted at runtime according to the given resource requirements and response time. Such adaptable services may be required by real time safety-critical applications. The flexibility introduced in executing adaptable OS services also gives rise to a potential safety problem. Thus, online model checking is integrated to the operating system so as to improve the dependability, reliability, and fault tolerance of these adaptable OS services.