Abstract: Techniques for extending operating system subsystems are provided. The techniques involve receiving a library that provides functions that extend an application program interface of the subsystem of the operating system. The techniques dynamically add a set of local procedure call ports or system call numbers corresponding to functions provided by the library and provide a known local procedure call port for receiving requests to identify a dynamically added local procedure call port or system call number. When a function of the library is requested, the subsystem determines the dynamically added port or system call number corresponding to the function, and provides an indication of the determined port or system call number to a requester of the function. The requester of the function may then invoke the function using the indicated dynamically added port or system call number.

Abstract: A facility for measuring code coverage of an executable object is described. The facility requests an identification of basic blocks of the executable object, adds a data structure to the executable object for storing code coverage information, and adds to each basic block of the executable object program instructions for updating an element of the data structure corresponding to the basic block. When the executable object performs, each basic block that is performed updates an element of the added data structure corresponding to the basic block. When the executable object terminates, it updates a file comprising an indication of basic blocks that have been performed.

Abstract: A facility for debugging in an operating system with native and non-native subsystems is described. The facility employs a debugger designed for use with the native subsystem. The debugger receives an indication to debug the application program of the non-native subsystem, attaches to the application program of the non-native subsystem, and when it receives an indication that the application program has started a new process, attaches to an executable component operating in the new process. When the debugger is appropriately configured, the facility attaches to an application program operating on the non-native subsystem rather than a terminal component operating on the native subsystem. When the debugger is appropriately configured, the facility redirects exceptions the debugger receives to the non-native subsystem.

Abstract: A facility for debugging in an operating system with native and non-native subsystems is described. The facility employs a debugger designed for use with the native subsystem. The debugger receives an indication to debug the application program of the non-native subsystem, attaches to the application program of the non-native subsystem, and when it receives an indication that the application program has started a new process, attaches to an executable component operating in the new process. When the debugger is appropriately configured, the facility attaches to an application program operating on the non-native subsystem rather than a terminal component operating on the native subsystem. When the debugger is appropriately configured, the facility redirects exceptions the debugger receives to the non-native subsystem.

Abstract: Techniques for enabling inter-subsystem resource sharing are provided. A subsystem executing an application (“app subsystem”) receives resources from another subsystem providing a resource (“resource subsystem”), such as a DLL. Then, when an application of the app subsystem is executed, the application may request a resource from the app subsystem, such as a DLL. The app subsystem, upon determining that the requested resource is associated with the resource subsystem, may communicate with the resource subsystem to request the resource. The resource subsystem may then load the resource. When the application utilizes the resource to perform an activity, such as by invoking a method of the DLL, the app subsystem may communicate with the resource subsystem to request the resource to perform the activity. The resource subsystem may provide an indication of a result to the resource subsystem upon completing the activity.

Abstract: Techniques for improving operating system performance are provided. A subsystem of an operating system operates as a kernel mode component, such as a kernel mode driver, instead of operating as a user mode component.

Abstract: Techniques for extending operating system subsystems are provided. The techniques involve receiving a library that provides functions that extend an application program interface of the subsystem of the operating system. The techniques dynamically add a set of local procedure call ports or system call numbers corresponding to functions provided by the library and provide a known local procedure call port for receiving requests to identify a dynamically added local procedure call port or system call number. When a function of the library is requested, the subsystem determines the dynamically added port or system call number corresponding to the function, and provides an indication of the determined port or system call number to a requester of the function. The requester of the function may then invoke the function using the indicated dynamically added port or system call number.

Abstract: Techniques for routing exceptions to operating system subsystems are provided. In various embodiments, a software developer may add a global exception handler software component to an application. The global exception handler may operate in a process relating to a subsystem. Upon receiving an exception, the global exception handler may route the exception to another subsystem.

Abstract: Techniques for extending operating system subsystems are provided. The techniques involve using a subsystem of an operating system having a set of insertion points that identify points in the program logic of the subsystem where logic extensions may be added. The subsystem may receive a library that has functions comprising program logic for extending the subsystem and a list that provides a correspondence between the insertion points and the functions. When the subsystem receives a request to perform an action that has a corresponding insertion point for which the list provides an associated function, the subsystem may perform the function. The function may be indicated to be performed at various points in the program logic of the subsystem, including before or after the requested action.

Abstract: Techniques for enabling inter-subsystem resource sharing are provided. The techniques include providing an RPC client on a first subsystem for acting as a proxy for a resource of a second subsystem. When the first subsystem receives a request from an application to access the resource, the RPC client may invoke a function of an RPC server associated with the second subsystem. The RPC server may load the resource on the second subsystem. The RPC client may then act as a proxy for the resource.