| 摘要 |
<p>The present invention is a method of encapsulating an operating system that fully implements protected mode within a second operating system that also fully implements protected mode. In a preferred embodiment, the Windows NT operating system is encapsulated within the INtime real-time operating system, thereby providing a user with a powerful GUI to use when developing and running applications that require a bounded interrupt latency. An encapsulation application (94) running under Windows NT uses a protection level 0 driver (88) to load a boot image (96) of the INtime operating system. The driver saves in global variables the addresses of the Windows NT GDT (272) and IDT (260), then loads pointers to the INtime GDT (258) and IDT (260) into the appropriate CPU registers (12), and causes a jump to the INtime operating system, which begins its initialization. INtime runs an encapsulation subsystem (114) that prepares a single task in which Windows NT is run in under INtime. When the user requests the use of Windows NT or when NT services are required, the encapsulation subsystem causes a switch back to the Windows NT task, which continues to run the driver. The driver then reloads the Windows NT GDT and IDT. Windows NT is therefore unaware that it is running as a task in another operating system. The GDT and IDT from Windows NT contain no information about INtime. The INtime GDT, on the other hand, contains descriptors of the segments used by Windows NT and its IDT, and INtime can control the operation of both operating systems to ensure a predictable response to real-time processes. By writing codes and a data pointer into registers, messages are passed between operating systems and real-time extensions to Windows NT.</p> |
