Книга: Microsoft Windows Embedded CE 6.0 Exam Preparation Kit

Chapter Review

The adaptation of a BSP is one of the most complicated and critical development tasks that OEMs face when porting Windows Embedded CE 6.0 to a new hardware platform. To facilitate this undertaking, Microsoft provides reference BSPs with Platform Builder and encourages OEMs to start the development process by cloning the most suitable BSP. The PQOAL-based BSPs follow a well-organized folder and file structure to separate platform-agnostic and platform-specific code by processor type and OAL function so that OEMs can focus on platform-specific implementation details without getting side tracked by general aspects of the kernel or operating system.

OEM developers should consider the following recommendations to ensure a successful adaptation of a BSP:

? Study the Windows Embedded CE reference BSPs Windows Embedded CE BSPs follow a well-defined architecture with close relationships to the kernel. This makes it necessary to implement numerous APIs that the kernel requires to run the operating system. Knowing these APIs and their purpose is very important. The PQOAL-based architecture is continually evolving.

? Clone a BSP Avoid writing a new BSP completely from scratch. Instead, clone a BSP to jump start the adaptation process. By reusing as much code as possible from a reference BSP, you not only shorten development time, but also increase the quality of your solution and provide a solid foundation for efficient handling of future upgrades.

? Boot loader and BLCOMMON Use BLCOMMON and related libraries when implementing a boot loader because these libraries provide useful hardware-independent features for downloading run-time images and enabling users to interact with the target device during the startup process.

? Memory and BSPs Make sure you thoroughly understand how Windows Embedded CE 6.0 deals with physical and virtual memory. Configure <Boot loader>.bib and Config.bib files to provide accurate information about available memory to the operating system and adjust the entries in the OEMAddressTable, if necessary. Keep in mind that you cannot directly access physical memory in Windows Embedded CE. Use the correct memory-mapping APIs to map physical memory addresses to virtual memory addresses.

? Implement power management Implement the OEMIdle function to enable the system to switch the CPU into Idle mode. Consider implementing OEMPowerOff as well, if your platform supports power state transitions into Suspend mode in response to user actions or critical battery levels.

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