Intel MultiProcessor manual Hardware Specification, System Memory Configuration

3 Hardware Specification

This section outlines the minimal set of common hardware features necessary for the operating system to operate on multiple hardware platforms. The MP hardware specification defines how the components mentioned in Chapter 2 are implemented. Compliance to the specification involves the following aspects of hardware implementation:

∙System memory configuration

∙System memory cacheability and shareability

∙External cache implementation requirements

∙Control of memory contention (locking)

∙Ordering of posted memory writes

∙Multiprocessor interrupt control

∙Reset support

∙Interval timer usage

∙Support for fault-resilient booting

While the bulk of the MP hardware specification pertains to multiprocessor interrupt control, other areas also require some attention. The following sections take up each of these topics in turn.

3.1 System Memory Configuration

The MP memory specifications are based on the standard PC/AT memory map, which currently has a physical memory space of four gigabytes, as shown in see Figure 3-1. Physical memory should begin at 0 and be contiguous. Memory-mapped I/O devices should be mapped at the top of physical memory. The APIC default base memory addresses defined by this specification are 0FEC0_0000h and 0FEE0_0000h.

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