About MTRR Mapping (X8400, X8420, X8440)

This topic provides information about a paramater available on the Sun Blade X8400, X8420 and X8440 Server Modules. The MTRR Mapping parameter determines the method for programming CPU MTRRs when 4 Gbytes or more of memory is present. Two selections are possible: Discrete or Continuous. The table below describes both settings.

The MTRR Mapping parameter is accessible

MTRR Mapping Selection

Description

Discrete

Discrete leaves the PCI hole below the 4 Gbyte boundary undescribed.

Continuous

Continuous explicitly describes the PCI hole as noncachable. Continuous provides more efficient operation; it uses optimal performance.

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