Книга: Microsoft Windows Embedded CE 6.0 Exam Preparation Kit

Dynamically Mapped Virtual Addresses

Dynamically Mapped Virtual Addresses

The kernel can also manage the mapping of physical-to-virtual addresses dynamically, which is the technique used for all non-static mappings. A driver or DLL loaded into the kernel through LoadKernelLibrary can reserve a region of virtual memory in the kernel address space by calling VirtualAlloc and then map the virtual address to a physical address by creating a new page-table entry through a call to VirtualCopy. This is a common technique to map virtual addresses to the registers or frame buffers of peripheral devices in order to perform input/output operations. If the mapped buffer is no longer needed, the device driver or DLL can call VirtualFree to remove page-table entry and free the allocated virtual memory.

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