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AMD CS5535 manual Model Specific Registers2, Example MSR Transaction, Rdmsr, Wrmsr

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Model Specific Registers2

Model Specific Registers	32430C

Model Specific Registers2

There are two ways to read or write Model Specific Registers (MSRs) in a Geode™ GX processor system. Software run- ning on the processor can use the RDMSR and WRMSR instructions, and modules within the processor can use the GeodeLink™ MSR transactions. The second method allows debug modules, such as the System Navigator from FS2 (First Silicon Solutions), to program MSRs.

All MSRs are 64 bits wide. The MSR addresses are 32 bits, where each unique address refers to a 64-bit data quantity.

To communicate with modules on the GeodeLink interface, the address of that module must be known. Addresses are obtained by either scanning the GeodeLink interface or having prior knowledge of the chip topology. This is discussed in detail in Section 3.0 "GeodeLink™ Architecture" on page 13.

RDMSR:

Input

ECX - Address to read.

Output

EDX:EAX - 64 bits data returned.

WRMSR:

Input

ECX - Address to write.

EDX:EAX - 64 bits data written.

Output

None.

2.1Example MSR Transaction

Read and write extended CPUID registers.

This example will change the CPUID.

RDMSR:

Load MSR specified by ECX into EDX:EAX.

WRMSR:

Write the value in EDX:EAX to MSR specified by ECX.

MSR_CPUID0 EQU 00003000h

MSR_CPUID1 EQU 00003001h

mov	ecx, MSR_CPUID0
RDMSR		; get values
mov	edx, ‘cdeR’	; write edx:eax to MSR in ecx. No change to eax.
WRMSR
mov	ecx, MSR_CPUID1
RDMSR
mov	edx, ‘duol’	; No change to eax
WRMSR
; Done

AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide			11

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AMD CS5535 manual Model Specific Registers2, Example MSR Transaction, Rdmsr, Wrmsr

Contents

AMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide Publication ID 32430CAMD Geode GX Processor CS5535 Companion Device GeodeROM Porting Guide AprilAMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide 2006 Advanced Micro Devices, Inc. All rights reservedTrademarks 2.0 Model Specific Registers Contents6.0 Setup Options 7.0 Memory Map Appendix A Support Documentation List of Figures List of Tables 1.0 OverviewAMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide Contents32430C Figure 7-1. GLIU Descriptor Map Figure 7-3. CPU Core Cache Region ConfigurationsList of Figures Figure 3-1. GeodeLink Architecture Topology Figure 4-1. Clock ControlAMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide 32430CList of Figures List of Tables Table 4-1. Default Region Configuration Properties Bit DescriptionsList of Tables Table 4-2. Diverse Device I/O LocationsAMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide 32430CList of Tables 1.2 Assumption Overview11.1 Introduction AMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide 32430CAssumption WRMSR Model Specific Registers22.1 Example MSR Transaction RDMSRAMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide 32430CModel Specific Registers CS5535 GeodeLink Architecture3AMD Geode GX Processor3.2.1 Memory Descriptor Types 3.1 GeodeLink MSR Addressing3.2 Descriptors 3.1.1 Addressing ExampleFigure 4-1. Clock Control 4.1.1 Set Clocks and ResetInitialization4 4.1 Processor Initialization4.1.2.1 CPU Identification 4.1.2 Calculating Processor Speed4.1.3 Memory Controller Initialization 4.1.3.1 Size Memory 4.1.4 Test Extended DRAM4.1.5 GeodeLink Modules Initialization 4.1.5.1 GLIU Descriptors Initialization Table 4-1. Default Region Configuration Properties Bit Descriptions4.1.5.3 Cache Setup 4.1.5.4 Region ConfigurationMSR Address GLPCI RegionsDescriptor Allocation Descriptor4.2.3 GLIU Initialization 4.2 AMD Geode CS5535 Companion Device Initialization4.2.1 Chipset ID 4.2.2 Set ID Select IDSEL4.2.4.3 System Management Bus SMBus 4.2.4.5 Multi Function General Purpose Timers MFGPTs4.2.4.1 IRQ Mapper 4.2.4.2 Keyboard Emulation Logic KEL 1+4.2.4.9 Other Legacy DD Initialization 4.2.4.7 Power Management Logic4.2.4.6 ACPI 4.2.4.8 Flash Interface4.2.7 AC97 Audio Controller Initialization Table 4-2. Diverse Device I/O Locations4.2.5 ATA-5 / Hard Drive Initialization 4.2.6 Universal Serial Bus USB4.3.1 Allocate Processor Frame Buffer and VSA2 Memory 4.3 Virtual System Architecture Initialization4.4 PCI Bus Initialization 4.2.8 GeodeLink Control Processor Initialization4.5.1.2 Dual Monitor Support 4.5 Miscellaneous Initializations4.5.1 Initialize Graphics Subsystem 4.5.1.1 Monochrome SupportAMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide 32430CInitialization 5.1.2 Scratchpad Initialization Implementation55.1 Implementation 5.1.1 ClockingAMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide 32430CImplementation Setup Options6 AMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide 32430CFigure 7-2. CPU Core Cache Descriptors Memory7MapFigure 7-1. GLIU Descriptor Map Figure 7-3. CPU Core Cache Region Configurations AMD Geode GX Processor/CS5535 Companion Device GeodeROM Porting Guide Figure 7-4. GeodeROM Flow - GX Processor/CS5535 DeviceMemory Map 32430C32430C Figure 7-4 GeodeROM Flow - GX Processor/CS5535 Device ContinuedPDF Date A.1 Document Revision HistoryTable A-1. Revision History Revision #