About Summary of Guidelines

The following is a summary of guidelines for memory allocation and usage in kernel-mode drivers. 

·         Do not make assumptions about the hardware platform, the pointer size, or the location or size of the virtual address spaces. Make your driver platform-independent by using macros, types, and system-defined constants, such as PHYSICAL_ADDRESS, PAGE_SIZE, and so forth.

·         Lay out data structures efficiently, considering natural and cache-line alignment and the processor page size. When possible, reuse allocated data structures. For more information about using memory efficiently, see “Six Tips for Efficient Memory Use,” which is listed in the Resources section at the end of this paper.

·         Allocate only as much memory as your device and driver require for normal operations.

·         Always check the translated resources to determine whether your device registers are mapped into memory or I/O space.

·         Do not allocate excessive amounts of memory that your driver might never use. Your device must coexist with other hardware and applications.

·         Use the system’s DMA routines. Replacing them with your own routines is almost guaranteed to cause your driver to fail on some hardware configurations.

·         Use lookaside lists when your driver needs fixed-size, reusable buffers.

·         Test your driver with as many different tools, and on as many different hardware configurations, as possible.