Книга: Microsoft Windows Embedded CE 6.0 Exam Preparation Kit

User-Mode Drivers Registry Settings

User-Mode Drivers Registry Settings

On Windows Embedded CE 6.0, you can run multiple user-mode drivers in a single host process or have multiple host processes enabled on the system. Drivers grouped in a single Udevice.exe instance share the same process space, which is particularly useful for drivers that depend on each other. However, drivers in the same process space can affect each other's stability. For example, if a user-mode driver causes the host process to fail, all drivers in that host process fail. The system continues to function except for the affected drivers and applications accessing these drivers, yet it is possible to recover from this situation by reloading the drivers, if the applications support it. If you isolate a critical driver in a separate user mode driver host process, you can increase the overall system stability. By using the registry entries listed in Table 6-5, you can define individual host process groups.

Table 6-5 Registry entries for user-mode driver host processes

Having defined the desired host process groups, you can associate each user-mode driver with a particular group by adding the UserProcGroup registry entry to the device driver's registry subkey (see Table 6-3 earlier in this lesson). By default, the UserProcGroup registry entry does not exist, which corresponds to a configuration in which Device Manager loads every user-mode driver into a separate host process instance.

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