While the use of Linux continues to sail along at a nice clip, the number of people kicking the tires is shrinking, for all the right reasons.
The Linux operating system (OS) has earned strong interest and adoption from those in the embedded software development community who are looking for cost-effective OS support for their latest embedded devices. In parallel, proprietary real-time OSs (RTOSs) offering robust arrays of services that are comparable to those in Linux have gained attention for safety-critical systems and large-scale telecommunications networks. In such applications, these complex RTOSs provide the capabilities that are needed, often including virtual memory, multiple independent levels of security (MILS), and volumes of middleware for security, communications protocols, and support for an array of development systems.
http://www.embedded.com/columns/guest/204801349;jsessionid=4GFJVTMTHP0NKQSNDLPCKHSCJUNN2JVP?pgno=1