Geode GXLV Processor Series Low Power Integrated x86 Solutions

Geode GXLV Processor SeriesIntegrated Functions (Continued)Bit Name DescriptionTable 4-44. PCI Configuration Registers (Continued)Index 44h PCI Arbitration Control 2 Register (R/W) Default Value = 00h7 PP Ping-Pong:0 = Arbiter grants the processor bus per the setting of bits [2:0].1 = Arbiter grants the processor bus ownership of the PCI bus every other arbitration cycle.6:4 FAC Fixed Arbitration Controls: These bits control the priority under fixed arbitration. The priority table is asfollows (priority listed highest to lowest):000 = REQ0#, REQ1#, REQ2#001 = REQ1#, REQ0#, REQ2#010 = REQ0#, REQ2#,REQ1#011 = Reserved100 = REQ1#, REQ2#, REQ0#101 = Reserved110 = REQ2#, REQ1#, REQ0#111 = REQ2#, REQ0#, REQ1#Note: The rotation arbitration bits [2:0] must be set to 000 for full fixed arbitration. If rotation bits are notset to 000, then hybrid arbitration will occur. If Ping-Pong is enabled (bit 7 = 1), the processor willhave priority every other arbitration. In this mode, the arbiter grants the PCI bus to a master andignores all other requests. When the master finishes, the processor will be guaranteed access. Atthis point PCI requests will again be recognized. This will switch arbitration from CPU to PCI toCPU to PCI, etc.3 RSVD Reserved: Set to 0.2:0 RAC Rotating Arbitration Controls: These bits control the priority under rotating arbitration.000 = Fixed arbitration will occur.111 = Full rotating arbitration will occur.When these bits are set to other values, hybrid arbitration will occur.Index 45h-FFh Reserved Default Value = 00hwww.national.com 172 Revision 1.3