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CPUID Identification Algorithms - tm

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23913A/0-November 2000 Preliminary Information Embedded AMD-K6™ Processors BIOS Design Guide CPUID Identification Algorithms The CPUID instruction provides information about the processor (vendor, type, name, etc.) and its capabilities (features). After detecting the processor and its capabilities, software can be accurately tuned to the system for maximum performance and benefit to users. For more detailed information about using the CPUID instruction, see "Embedded AMD Processor Recognition" on page 57. To determine if the processor is enabled with AMD PowerNow! technology, use CPUID function 8000_0007, as described on page 79. The recommended boot strings (or processor names) to be displayed for AMD-K6 processors are shown in Table 5. Table 5. Recommended Boot Strings for AMD-K6™ Processors Model Recommended Boot String Display1 Model 7 AMD-K6(tm)/XXX All steppings of Models 8 AMD-K6(tm)-2/XXX Model D/[7:4]2 AMD-K6(tm)-2+/XXX Model 9/[3:0] AMD-K6(tm)-III/XXX Model D/[3:0]2 AMD-K6(tm)-III+/XXX Notes: 1. The value for XXX is determined by calculating the core frequency of the processor. Use the Time Stamp Counter (TSC) to 'clock' a timed operation and compare the result to the real-time clock (RTC) to determine the operating frequency. 2. See "Functions 8000_0002h, 8000_0003h, and 8000_0004h - Processor Name String" on page 77 for more information about these steppings. For example, a BIOS boot string for a Model 9, stepping 3, 450MHz AMD-K6-III processor would look like this: s AMD-K6(tm)-III/450 Figure 1 on page 12 shows a flow chart for the CPUID instruction. Use this chart to implement a CPUID algorithm. CPUID Identification Algorithms 11

Section	Page
Contents	3
List of Figures	7
List of Tables	9
Revision History	11
Introduction	13
Audience	13
Processor Models and Steppings	14
AMDK6™E Embedded Processor	15
Model 7	15
AMDK6™2 Processor	15
Model 8/[7:0]	15
Model 8/[F:8]	15
AMDK6™2E Embedded Processor	16
Model 8/[F:8]	16
AMDK6™2E+ Embedded Processor	16
Model D/[7:4]	16
AMDK6™III Processor	17
Model 9/[3:0]	17
AMDK6™IIIE+ Embedded Processor	17
Model D/[3:0]	17
BIOS Consideration Checklist	18
CPUID	18
CPU Speed Detection	18
ModelSpecific Registers (MSRs)	18
Cache Testing	19
SMM Issues	19
States after RESET and INIT	20
Register States after RESET and INIT	20
Processor State after INIT	21
BuiltIn SelfTest (BIST)	22
CPUID Identification Algorithms	23
System Management Mode (SMM)	25
StateSave Map Differences	25
I/O Trap Dword Differences	25
ModelSpecific Registers Overview	26
Standard Model-Specific Registers (All Models)	28
MachineCheck Address Register (MCAR) and MachineCheck Type Register (MCTR)	28
Test Register 12 (TR12)	28
Time Stamp Counter (TSC)	28
Model 7 and Model 8/[7:0] Registers	29
Extended Feature Enable Register (EFER)	30
Write Handling Control Register (WHCR)	31
Write Allocation	31
Write Cacheability Detection Enable Bit	32
Write Allocate Enable Limit Field	32
Write Allocate Enable 15to16Mbyte Field.	33
SYSCALL/SYSRET Target Address Register (STAR)	34
Model 8/[F:8] Registers	35
Extended Feature Enable Register (EFER)	36
External Write Buffer Empty Control Field	36
Write Handling Control Register (WHCR)	39
Write Allocation	39
Write Allocate Enable Limit Field	40
Write Allocate Enable 15to16Mbyte Field	41
UC/WC Cacheability Control Register (UWCCR)	42
Physical Base Address n (n=0, 1)	43
Physical Address Mask n (n=0, 1)	43
WCn (n=0, 1)	43
UCn (n=0, 1)	43
Memory-Range Restrictions	44
Examples	45
Processor State Observability Register (PSOR)	46
NOL2 Bit	46
STEP Field	46
BF Field	46
Page Flush/Invalidate Register (PFIR)	48
LINPAGE Field	48
PF Bit	48
F/I Bit	49
Model 9 Registers	50
Extended Feature Enable Register (EFER)	51
Level-2 Cache Array Access Register (L2AAR)	52
LRU (Least Recently Used) Field	55
Writing to L2 Tag of AMDK6™III Processor	55
Model D Registers	57
Processor State Observability Register (PSOR) (Low-Power Versions)	58
PBF[2:0] Field	58
VID Field	58
NOL2 Bit	59
STEP Field	59
EBF[2:0] Field	59
Level-2 Cache Array Access Register (L2AAR)	60
LRU (Least Recently Used) Field	64
Writing to L2 Tag of AMDK6IIIE+ Processor	65
Enhanced Power Management Register (EPMR) (Low-Power Versions)	66
EPM 16-Byte I/O Block (Low-Power Versions Only)	67
BVC Field	67
Embedded AMD Processor Recognition	69
CPUID Instruction Overview	69
Testing for the CPUID Instruction	70
Illegal Instruction Exception Method	70
EFLAGS IDBit Method	70
Using CPUID Functions	71
Identifying the Processor’s Vendor	72
Testing For Extended Functions	73
Determining the Processor Signature	73
Identifying Supported Features	75
Determining Instruction Set Support	76
Detection Algorithm for Determining Instruction Set Support	77
CPUID Test	77
Standard Function Test	77
MMX™ Test	77
Optional SSE Test	77
Extended Functions Test	77
3DNow!™ Test	77
Vendor Check	77
3DNow! Extensions Test	78
AMD Multimedia Instruction Extensions Test	78
AMD Processor Signature (Extended Function)	78
Displaying the Processor’s Name	78
Displaying Cache Information	79
Determining AMDPowerNow!™ Technology Information	79
Sample Code	79
New AMDK6™ Processor Instructions	80
Additional Considerations	81
Software Timing Dependencies Relative to Memory Controller Setup	81
Pipelining Support	81
Read-Only Memory	82
Appendix A	83
CPUID	83
Standard Functions	84
Extended Functions	87
Cache Associativity Field Definitions	92
Associativity for L1 Caches and L1 TLBs	92
Associativity for L2 Cache	92
Appendix B	93
Values Returned by the CPUID Instruction	93