RT-Linux is simple, providing only a bare minimum of functionality necessary for implementing a real-time system. But this simplicity is to the system designer's benefit. You want to implement the bulk of the application in Linux processes because Linux itself is solid, stable, and popular with a lot of desktop users-so you know you can get help if you have trouble. Real-time tasks should have only the functionality necessary to perform real-time I/O and pass data to and from the Linux processes. The simplicity of RT-Linux has two advantages: first, its very simplicity makes it less likely that it will be buggy; and second, if you do find a bug, it's likely to be easy to find and fix. These factors are important. Because real-time systems are a minuscule portion of Linux applications, the amount of help you can find for developing code using RT-Linux is certain to be low. So a feature-rich RT-Linux is not necessarily something to be desired. The functionality now implemented is also sufficient for the vast majority of real-time systems if properly used.
Linux is clearly not the best platform for all embedded PCs. Because of its size, a full GUI-based system must be implemented as a disk-based system or one connected to a network from which it can boot. Still, a large and growing number of embedded applications can run with a disk and need the GUI and networking features that are built into Linux. For example, many medical devices must have attractive user interfaces to be competitive, and industrial machine controls must have both GUIs and networking. Patching together such a system with DOS or a low-end RTOS is impractical. Inflating the selling price with a $700 royalty paid to a high-end RTOS vendor is out of the question. Linux provides a way to incorporate these features for free. And not only are they free, they are usually more up-to-date than those supplied by RTOS vendors, who usually provide features well after they are available on desktop OSs.
对不起各位，我的积分不多，但我要翻译的内容不少，我真诚的希望大家给我帮助，我将非常感谢，真诚的恳求不要机译！谢谢！