PCI-X Protocol Addendum to the PCI Local Bus Specification Revision 2.0a

PCI-X Protocol Addendum to the PCI Local Bus Specification Revision 2.0a July 22, 2003

REVISION REVISION HISTORY DATE 1.0 Initial release. 9/22/99 1.0a Clarifications and typographical corrections. 7/24/00 1.0b Clarifications and errata. 7/29/02 2.0 2.0a Added Mode 2 with 1.5V signaling, source-synchronous clocking of two or four subphases per clock. Added, device ID messaging, and 16-bit interface. Incorporated the PCI-X slot and card identification ECN Incorporated errata through revision A.26. Added Acknowledgements section. 7/29/02 7/22/03 The PCI-SIG disclaims all warranties and liability for the use of this document and the information contained herein and assumes no responsibility for any errors that may appear in this document, nor does the PCI-SIG make a commitment to update the information contained herein. Contact the PCI-SIG office to obtain the latest revision of the specification. Questions regarding the PCI-X Addendum or membership in the PCI-SIG may be forwarded to: Membership Services http://www.pcisig.com E-mail: administration@pcisig.com Phone: 503-291-2569 800-433-5177 (USA Only) Fax: 503-297-1090 Technical Support techsupp@pcisig.com DISCLAIMER This PCI-X Addendum is provided as is with no warranties whatsoever, including any warranty of merchantability, noninfringement, fitness for any particular purpose, or any warranty otherwise arising out of any proposal, specification, or sample. The PCI-SIG disclaims all liability for infringement of proprietary rights, relating to use of information in this specification. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted herein. All product names are trademarks, registered trademarks, or servicemarks of their respective owners. Copyright 1999, 2000, 2002, 2003 PCI-SIG 2

Contents PREFACE... 19 1. INTRODUCTION... 21 1.1. DOCUMENTATION CONVENTIONS... 25 1.2. TERMS AND ABBREVIATIONS... 27 1.3. FIGURE LEGEND... 37 1.4. COMPARISON OF TRANSACTIONS IN DIFFERENT BUS MODES... 39 1.5. BURST AND DWORD TRANSACTIONS... 44 1.6. WAIT STATES... 46 1.7. SPLIT TRANSACTIONS... 46 1.8. BUS WIDTH... 46 1.9. COMPATIBILITY AND SYSTEM INITIALIZATION... 47 1.10. DEVICE ID MESSAGING... 48 1.11. PCI-X MODE 2 BUS DRIVE AND TURN AROUND... 48 1.12. SUMMARY OF PROTOCOL RULES... 49 1.12.1. General Bus Rules... 49 1.12.2. Initiator Rules... 51 1.12.3. Target Rules... 53 1.12.4. Bus Arbitration Rules... 54 1.12.5. Configuration Transaction Rules... 56 1.12.6. Parity and Error Protection Rules... 56 1.12.7. Bus Width Rules... 58 1.12.8. Split Transaction Rules... 59 1.13. PCI-X TRANSACTION FLOW... 60 2. PCI-X TRANSACTION PROTOCOL... 63 2.1. SEQUENCES... 63 2.2. ALLOWABLE DISCONNECT BOUNDARIES AND BUFFER SIZE... 64 2.3. DEPENDENCIES BETWEEN ADDRESS, BYTE COUNT, AND BYTE ENABLES... 65 2.4. PCI-X COMMAND ENCODING... 70 2.5. ATTRIBUTES... 72 2.6. BURST TRANSACTIONS... 76 2.6.1. Burst Push Transactions... 78 2.6.1.1. Common-Clock Burst Push Transactions... 81 2.6.1.2. Source-Synchronous Burst Push Transactions... 85 2.6.2. Burst Reads... 89 2.7. DWORD TRANSACTIONS... 95 2.7.1. DWORD Memory and I/O Transactions... 96 2.7.2. Configuration Transactions... 97 2.7.2.1. Configuration Transaction Timing... 98 2.7.2.2. Configuration Transaction Address and Attributes... 100 2.7.3. Special Cycle Transactions... 103 2.7.4. Interrupt Acknowledge Transactions... 105 3

2.8. DEVICE SELECT TIMING... 105 2.8.1. Common-Clock Burst Push and DWORD Write Transactions... 106 2.8.2. Source-Synchronous Burst Push Transactions... 109 2.8.3. Reads... 110 2.9. WAIT STATES... 113 2.9.1. Target Initial Latency... 113 2.9.2. Wait States on Burst Push and DWORD Write Transactions... 116 2.9.3. Wait States on Reads... 122 2.10. SPLIT TRANSACTIONS... 127 2.10.1. Basic Split Transaction Requirements... 127 2.10.2. Split Completion... 130 2.10.3. Split Completion Address... 132 2.10.4. Completer Attributes... 134 2.10.5. Requirements for Accepting Split Completions... 137 2.10.6. Split Completion Messages... 137 2.10.6.1. Write Completion Message Class... 139 2.10.6.2. Completer Error Message Class... 139 2.11. TRANSACTION TERMINATION... 141 2.11.1. Initiator Termination... 142 2.11.1.1. Initiator Disconnection or Satisfaction of Byte Count... 142 2.11.1.2. Master-Abort Termination... 146 2.11.2. Target Termination and Data Phase Signaling... 147 2.11.2.1. Single Data Phase Disconnection... 148 2.11.2.2. Disconnection at Next ADB... 151 2.11.2.3. Retry Termination... 154 2.11.2.4. Split Response Termination... 155 2.11.2.5. Target-Abort Termination... 156 2.12. BUS WIDTH... 158 2.12.1. 64-Bit and 32-Bit Bus Width... 158 2.12.1.1. Address Width... 159 2.12.1.2. Attribute Width... 162 2.12.1.3. Data Transfer Width... 162 2.12.2. 16-Bit Bus Width... 173 2.12.2.1. Address Width... 176 2.12.2.2. Attribute Width... 176 2.12.2.3. Data Transfer Width... 177 2.12.2.3.1. Burst Transactions on a 16-Bit Bus... 177 2.12.2.3.2. DWORD Transactions on a 16-Bit Bus... 182 2.12.2.3.3. Target Data Phase Signaling on a 16-Bit Bus... 183 2.13. REQUIRED ACCEPTANCE AND COMPLETION RULES FOR SIMPLE DEVICES... 185 2.14. QUIESCING DEVICE OPERATION... 187 2.15. SNOOPING PCI-X TRANSACTIONS... 188 2.16. DEVICE ID MESSAGING... 189 2.16.1. Device ID Message Address... 191 2.16.2. Device ID Message Attributes... 193 2.16.3. Device ID Message Format... 194 4

2.16.3.1. Vendor-Defined Message Class... 195 2.16.3.2. Reserved Message Classes... 195 2.17. PCI-X MODE 2 BUS DRIVE AND TURN-AROUND... 195 3. DEVICE REQUIREMENTS... 197 3.1. SOURCE SAMPLING... 197 3.2. MESSAGE-SIGNALED INTERRUPTS... 198 3.3. PCI POWER MANAGEMENT... 198 4. ARBITRATION... 201 4.1. ARBITRATION PARKING AND BUS TURN-AROUND... 201 4.1.1. PCI-X Mode 1 Arbitration Parking... 201 4.1.2. PCI-X Mode 2 Bus Drive and Turn-Around... 202 4.1.2.1. Bus Turn-Around Alert and Bus Turn-Around... 203 4.1.2.2. Interface Low-Power State... 208 4.1.2.3. Bus State Initialization... 212 4.2. ARBITRATION SIGNALING PROTOCOL... 212 4.2.1. Device Requirements... 214 4.2.2. Arbiter Requirements... 216 4.3. ARBITER COORDINATION WITH THE PCI HOT-PLUG CONTROLLER... 218 4.4. LATENCY TIMER... 218 5. ERROR FUNCTIONS... 219 5.1. BUS ERROR PROTECTION... 219 5.1.1. Parity Mode... 220 5.1.1.1. Parity Generation... 221 5.1.1.2. Parity Checking... 221 5.1.1.3. Parity Timing... 222 5.1.2. Mode... 226 5.1.2.1. Basics and Definitions... 228 5.1.2.2. Signature Generation... 229 5.1.2.2.1. Seven-Bit Description... 230 5.1.2.2.2. Eight-Bit Description... 232 5.1.2.2.3. Phase Protection Description... 234 5.1.2.3. Checking... 237 5.1.2.4. Timing... 239 5.1.3. on 16-Bit Transfers... 253 5.1.4. Driving SERR#... 258 5.2. ERROR HANDLING AND FAULT TOLERANCE... 258 5.2.1. Uncorrectable Data Errors... 258 5.2.1.1. Devices and Software Drivers that Support Recovery from Uncorrectable Data Errors... 259 5.2.1.2. Devices or Software Drivers That Do Not Support Recovery from Uncorrectable Data Errors... 260 5.2.1.3. Uncorrectable Data Errors in Split Response for Read Transactions 261 5.2.2. Target-Abort and Master-Abort Exceptions... 262 5

5.2.3. Uncorrectable Address and Attribute Errors... 262 5.2.4. Split Transaction Errors... 262 5.2.5. Corrupted or Unexpected Split Completions... 263 5.2.6. Reporting Split Completion Error Messages... 264 6. SYSTEM INTEROPERABILITY AND INITIALIZATION... 267 6.1. INTEROPERABILITY... 267 6.1.1. Device and Add-In Card Interoperability Requirements... 267 6.1.2. System Interoperability Requirements... 268 6.1.3. Interoperability Matrix... 269 6.2. INITIALIZATION REQUIREMENTS... 270 6.2.1. Device and Add-in Card Initialization Requirements... 274 6.2.2. System Initialization Requirements... 276 6.2.3. Mode and Frequency Initialization Sequence... 278 6.2.3.1. System Power-Up... 278 6.2.3.2. Hot Insertion in a PCI-X System... 279 6.2.4. Device Number and Bus Number Initialization... 280 7. CONFIGURATION SPACE FOR TYPE 00H HEADER DEVICES... 283 7.1. PCI-X EFFECTS ON CONVENTIONAL CONFIGURATION SPACE HEADER... 283 7.2. PCI-X CAPABILITIES LIST ITEM... 285 7.2.1. PCI-X ID... 286 7.2.2. Next Capabilities Pointer... 286 7.2.3. PCI-X Command Register... 286 7.2.4. PCI-X Status Register... 289 7.2.5. Control and Status Register... 296 7.2.6. Address Registers... 299 7.2.7. Attribute Register... 300 7.3. USE OF I/O SPACE... 300 7.4. MODE 2 CONFIGURATION SPACE... 301 7.4.1. Enhanced Configuration Access Mechanism... 301 7.4.2. Extended Capabilities List Items... 303 8. PCI-X BRIDGE ADDITIONAL DESIGN REQUIREMENTS... 307 8.1. SUMMARY OF KEY REQUIREMENTS... 307 8.2. PCI-X BRIDGES AND APPLICATION BRIDGES... 308 8.3. ADDRESS DECODING... 309 8.4. BRIDGE OPERATION... 309 8.4.1. Buffer Size Requirements... 309 8.4.2. Forwarding Split Transactions... 311 8.4.2.1. Split Completion Buffer Allocation... 313 8.4.2.2. Immediate Completion by the Completer... 316 8.4.2.3. Split Request Capacity Recommendations... 317 8.4.3. Connecting PCI-X and Conventional PCI Interfaces... 318 8.4.3.1. Conventional Requester, PCI-X Completer... 318 8.4.3.1.1. Conventional PCI to PCI-X Command Translation and Byte Count Generation 318 6

8.4.3.1.2. Delayed Transaction to Split Transaction Conversion... 320 8.4.3.1.3. Conventional PCI to PCI-X Attribute Creation... 320 8.4.3.2. PCI-X Requester, Conventional Completer... 321 8.4.3.2.1. PCI-X to Conventional PCI Command Translation... 321 8.4.3.2.2. Split Transaction to Delayed Transaction Conversion... 322 8.4.3.2.3. Creating a Split Completion... 323 8.4.4. Transaction Ordering and Passing Rules for Bridges... 323 8.4.5. Required Acceptance Rules for Bridges... 327 8.4.6. Forwarding Memory Write Transactions... 328 8.4.7. Forwarding Device ID Messages... 330 8.5. EXCLUSIVE ACCESS... 331 8.5.1. Starting an Exclusive Access... 333 8.5.2. Continuing an Exclusive Access... 336 8.5.3. Accessing a Locked Bridge... 337 8.5.4. Completing an Exclusive Access... 337 8.6. PCI-X BRIDGE (TYPE 01H) CONFIGURATION REGISTERS... 338 8.6.1. PCI-X Effects on Conventional Bridge Configuration Space Header... 338 8.6.2. PCI-X Bridge Capabilities List Item... 340 8.6.2.1. PCI-X ID... 341 8.6.2.2. Next Capabilities Pointer... 342 8.6.2.3. PCI-X Secondary Status Register... 342 8.6.2.4. PCI-X Bridge Status Register... 346 8.6.2.5. Upstream Split Transaction Register... 350 8.6.2.6. Downstream Split Transaction Register... 351 8.6.2.7. PCI-X Bridge Control and Status Register... 353 8.6.2.8. PCI-X Bridge Address Registers... 357 8.6.2.9. PCI-X Bridge Attribute Register... 357 8.7. PCI-X BRIDGE ERROR SUPPORT... 358 8.7.1. PCI-X Originating Bus... 358 8.7.1.1. Uncorrectable Data Errors... 358 8.7.1.1.1. Uncorrectable Data Error on an Immediate Read... 359 8.7.1.1.2. Uncorrectable Data Error on a Non-Posted Write... 359 8.7.1.1.3. Uncorrectable Data Error on a Split Completion... 360 8.7.1.1.4. Uncorrectable Data Error on a Posted Write... 360 8.7.1.2. Master-Abort... 360 8.7.1.3. Target-Abort... 362 8.7.2. Conventional PCI Originating Bus... 363 8.7.3. Forwarding Data-Phase Parity and Errors... 364 8.7.3.1. Parity to Parity... 364 8.7.3.2. to... 365 8.7.3.3. Parity to... 367 8.7.3.4. to Parity... 368 8.7.4. Bridge Internal Error Protection... 370 8.8. PCI-X BRIDGE ERROR CLASS SPLIT COMPLETION MESSAGE... 371 8.9. SECONDARY BUS MODE AND FREQUENCY INITIALIZATION SEQUENCE... 372 7

A. APPENDIX CONVENTIONAL PCI VS. PCI-X PROTOCOL RULE COMPARISON... 375 B. APPENDIX USE OF RELAXED ORDERING... 381 B.1. RELAXED WRITE ORDERING... 382 B.2. RELAXED READ ORDERING... 382 B.3. CO-LOCATION OF PAYLOAD AND CONTROL... 383 B.4. OTHER USES OF RELAXED ORDERING... 384 B.5. I 2 O USAGE MODELS... 384 B.5.1. I 2 O Messaging Protocol Operation... 385 B.5.2. Message Delivery with the Push Model... 385 B.5.3. Message Delivery with the Pull Model... 386 B.5.4. Message Delivery with the Outbound Option... 387 B.5.5. Message Delivery with Peer to Peer... 388 C. APPENDIX MINIMAL PCI POWER MANAGEMENT SUPPORT... 389 D. APPENDIX SETTING PERFORMANCE REGISTERS... 391 D.1. SETTING THE MAXIMUM MEMORY READ BYTE COUNT REGISTER... 391 D.2. OPTIMIZING THE SPLIT TRANSACTION COMMITMENT LIMITS IN PCI-X BRIDGES 391 E. APPENDIX APPLICATIONS... 393 E.1. IN MODE 1... 393 E.1.1. Mode 1 in Embedded Systems... 393 E.1.2. Mode 1 in Slot-Based Systems... 393 E.2. USE OF PCI-X IN MEMORY APPLICATIONS... 394 E.2.1. Features for Memory Applications... 394 E.2.2. Adjustments for Memory Applications... 395 E.3. CONVERTING BETWEEN WIDTHS... 396 E.3.1. Combining Signatures that Include Phase/Error Signatures... 396 E.3.2. Handling Combined Eight-Bit s in Recovery Software... 398 E.4. DETECTING SINGLE-PIN PROBLEMS ON THE 16-BIT BUS... 399 E.5. CHECK/CORRECT LOGIC EXAMPLE... 400 E.6. SELECTION OF PHASE PROTECTION SIGNATURES... 401 E.7. SUMMARY REQUIREMENTS TABLE... 402 E.8. SAMPLE TEST PATTERNS... 404 SEC ADDR... 408 F. APPENDIX SYSTEM ARCHITECTURE ISSUES... 413 F.1. WRITE ORDERING OBSERVED BY A READ SEQUENCE... 413 F.2. UPDATE ORDERING PROVIDED BY A WRITE SEQUENCE... 413 F.3. UPDATE GRANULARITY... 414 ACKNOWLEDGEMENTS... 415 8

Figures FIGURE 1-1: FIGURE LEGEND, MODE 1... 37 FIGURE 1-2: FIGURE LEGEND, MODE 2... 38 FIGURE 1-3: TYPICAL CONVENTIONAL PCI WRITE TRANSACTION... 40 FIGURE 1-4: TYPICAL PCI-X MODE 1 WRITE TRANSACTION... 41 FIGURE 1-5: TYPICAL PCI-X 266 (MODE 2) BURST WRITE TRANSACTION... 42 FIGURE 1-6: TYPICAL PCI-X 533 (MODE 2) BURST WRITE TRANSACTION... 42 FIGURE 1-7: TYPICAL 16-BIT PCI-X 266 (MODE 2) BURST WRITE TRANSACTION... 43 FIGURE 1-8: TYPICAL 16-BIT PCI-X 533 (MODE 2) BURST WRITE TRANSACTION... 43 FIGURE 1-9: TRANSACTION FLOW WITHOUT CROSSING A BRIDGE... 61 FIGURE 1-10: TRANSACTION FLOW ACROSS A BRIDGE... 62 FIGURE 2-1: BURST TRANSACTION REQUESTER ATTRIBUTE BIT ASSIGNMENTS... 72 FIGURE 2-2: DWORD TRANSACTION REQUESTER ATTRIBUTE BIT ASSIGNMENTS... 72 FIGURE 2-3: COMMON-CLOCK BURST MEMORY WRITE TRANSACTION WITH NO TARGET INITIAL WAIT STATES, MODE 1... 82 FIGURE 2-4: COMMON-CLOCK BURST MEMORY WRITE TRANSACTION WITH TWO TARGET INITIAL WAIT STATES, MODE 1... 83 FIGURE 2-5: COMMON-CLOCK BURST MEMORY WRITE TRANSACTION WITH NO TARGET INITIAL WAIT STATES, MODE 2... 84 FIGURE 2-6: COMMON-CLOCK BURST MEMORY WRITE TRANSACTION WITH TWO TARGET INITIAL WAIT STATES, MODE 2... 85 FIGURE 2-7: SOURCE-SYNCHRONOUS BURST PUSH TRANSACTION WITH NO TARGET INITIAL WAIT STATES... 87 FIGURE 2-8: SOURCE-SYNCHRONOUS BURST PUSH TRANSACTION WITH TWO TARGET INITIAL WAIT STATES... 88 FIGURE 2-9: BURST MEMORY READ TRANSACTION WITH NO TARGET INITIAL WAIT STATES, MODE 1... 91 FIGURE 2-10: BURST MEMORY READ TRANSACTION WITH TARGET INITIAL WAIT STATES, MODE 1... 92 FIGURE 2-11: BURST MEMORY READ TRANSACTION WITH NO TARGET INITIAL WAIT STATES, MODE 2... 93 FIGURE 2-12: BURST MEMORY READ TRANSACTION WITH TARGET INITIAL WAIT STATES, MODE 2... 94 FIGURE 2-13: I/O WRITE TRANSACTION WITH NO WAIT STATES AND DATA TRANSFER, MODE 1... 96 FIGURE 2-14: DWORD MEMORY OR I/O READ WITH TWO TARGET INITIAL WAIT STATES AND DATA TRANSFER, MODE 1... 96 FIGURE 2-15: I/O WRITE TRANSACTION WITH NO WAIT STATES AND DATA TRANSFER, MODE 2... 97 FIGURE 2-16: DWORD MEMORY OR I/O READ WITH TWO TARGET INITIAL WAIT STATES AND DATA TRANSFER, MODE 2... 97 FIGURE 2-17: CONFIGURATION WRITE TRANSACTION, MODE 1... 99 FIGURE 2-18: CONFIGURATION READ TRANSACTION, MODE 1... 99 FIGURE 2-19: CONFIGURATION WRITE TRANSACTION, MODE 2... 100 9

FIGURE 2-20: CONFIGURATION READ TRANSACTION, MODE 2... 100 FIGURE 2-21: CONFIGURATION TRANSACTION ADDRESS FORMAT... 101 FIGURE 2-22: TYPE 0 CONFIGURATION TRANSACTION REQUESTER ATTRIBUTE BIT ASSIGNMENTS... 103 FIGURE 2-23: SPECIAL CYCLE, MODE 1... 104 FIGURE 2-24: SPECIAL CYCLE, MODE 2... 104 FIGURE 2-25: DEVSEL# TIMING, SINGLE ADDRESS CYCLE, 64- OR 32-BIT BUS... 106 FIGURE 2-26: COMMON-CLOCK BURST MEMORY WRITE WITH DEVSEL# DECODE A AND NO INITIAL WAIT STATES, MODE 1... 107 FIGURE 2-27: COMMON-CLOCK BURST MEMORY WRITE WITH DEVSEL# DECODE B AND NO INITIAL WAIT STATES, MODE 1... 107 FIGURE 2-28: COMMON-CLOCK BURST MEMORY WRITE WITH DEVSEL# DECODE C AND NO INITIAL WAIT STATES, MODE 1... 108 FIGURE 2-29: COMMON-CLOCK BURST MEMORY WRITE WITH SUBTRACTIVE DEVSEL# DECODE AND NO INITIAL WAIT STATES, MODE 1... 108 FIGURE 2-30: COMMON-CLOCK BURST MEMORY WRITE WITH DEVSEL# DECODE B AND NO INITIAL WAIT STATES, MODE 2... 108 FIGURE 2-31: SOURCE-SYNCHRONOUS BURST PUSH TRANSACTION WITH DEVSEL# DECODE B AND NO INITIAL WAIT STATES... 109 FIGURE 2-32: SOURCE-SYNCHRONOUS BURST PUSH TRANSACTION WITH DEVSEL# DECODE C AND NO INITIAL WAIT STATES... 110 FIGURE 2-33: SOURCE-SYNCHRONOUS BURST PUSH TRANSACTION WITH SUBTRACTIVE DEVSEL# DECODE AND NO INITIAL WAIT STATES... 110 FIGURE 2-34: BURST READ WITH DEVSEL# DECODE A AND NO INITIAL WAIT STATES, MODE 1... 111 FIGURE 2-35: BURST READ WITH DEVSEL# DECODE B AND NO INITIAL WAIT STATES, MODE 1... 111 FIGURE 2-36: BURST READ WITH DEVSEL# DECODE C AND NO INITIAL WAIT STATES, MODE 1... 112 FIGURE 2-37: BURST READ WITH SUBTRACTIVE DEVSEL# DECODE AND NO INITIAL WAIT STATES, MODE 1... 112 FIGURE 2-38: BURST READ WITH DEVSEL# DECODE B AND NO INITIAL WAIT STATES, MODE 2... 112 FIGURE 2-39: BURST MEMORY WRITE TRANSACTION WITH DEVSEL# DECODE A AND TWO INITIAL WAIT STATES, MODE 1... 117 FIGURE 2-40: BURST MEMORY WRITE TRANSACTION WITH DEVSEL# DECODE A AND FOUR INITIAL WAIT STATES, MODE 1... 117 FIGURE 2-41: BURST MEMORY WRITE TRANSACTION WITH DEVSEL# DECODE B AND TWO INITIAL WAIT STATES, MODE 1... 118 FIGURE 2-42: BURST MEMORY WRITE TRANSACTION WITH DEVSEL# DECODE B AND FOUR INITIAL WAIT STATES, MODE 1... 118 FIGURE 2-43: BURST MEMORY WRITE TRANSACTION WITH DEVSEL# DECODE C AND TWO INITIAL WAIT STATES, MODE 1... 119 FIGURE 2-44: BURST MEMORY WRITE TRANSACTION WITH DEVSEL# DECODE C AND FOUR INITIAL WAIT STATES, MODE 1... 119 10

FIGURE 2-45: DWORD WRITE TRANSACTION WITH DEVSEL# DECODE A AND TWO INITIAL WAIT STATES, MODE 1... 120 FIGURE 2-46: DWORD WRITE TRANSACTION WITH DEVSEL# DECODE C AND TWO INITIAL WAIT STATES, MODE 1... 120 FIGURE 2-47: SOURCE-SYNCHRONOUS BURST PUSH TRANSACTION WITH DEVSEL# DECODE B AND TWO INITIAL WAIT STATES, MODE 2... 120 FIGURE 2-48: SOURCE-SYNCHRONOUS BURST PUSH TRANSACTION WITH DEVSEL# DECODE B AND FOUR INITIAL WAIT STATES, MODE 2... 121 FIGURE 2-49: SOURCE-SYNCHRONOUS BURST PUSH TRANSACTION WITH DEVSEL# DECODE C AND TWO INITIAL WAIT STATES, MODE 2... 121 FIGURE 2-50: SOURCE-SYNCHRONOUS BURST PUSH TRANSACTION WITH DEVSEL# DECODE C AND FOUR INITIAL WAIT STATES, MODE 2... 121 FIGURE 2-51: DWORD WRITE TRANSACTION WITH DEVSEL# DECODE C AND TWO INITIAL WAIT STATES, MODE 2... 122 FIGURE 2-52: BURST READ TRANSACTION WITH DEVSEL# DECODE A AND ONE INITIAL WAIT STATE, MODE 1... 123 FIGURE 2-53: BURST READ TRANSACTION WITH DEVSEL# DECODE A AND TWO INITIAL WAIT STATES, MODE 1... 123 FIGURE 2-54: BURST READ TRANSACTION WITH DEVSEL# DECODE A AND THREE INITIAL WAIT STATES, MODE 1... 123 FIGURE 2-55: BURST READ TRANSACTION WITH DEVSEL# DECODE A AND FOUR INITIAL WAIT STATES, MODE 1... 124 FIGURE 2-56: BURST READ TRANSACTION WITH DEVSEL# DECODE C AND TWO INITIAL WAIT STATES, MODE 1... 124 FIGURE 2-57: DWORD READ TRANSACTION WITH DEVSEL# DECODE A AND TWO INITIAL WAIT STATES, MODE 1... 124 FIGURE 2-58: DWORD READ TRANSACTION WITH DEVSEL# DECODE C AND TWO INITIAL WAIT STATES, MODE 1... 125 FIGURE 2-59: BURST READ TRANSACTION WITH DEVSEL# DECODE B AND ONE INITIAL WAIT STATE, MODE 2... 125 FIGURE 2-60: BURST READ TRANSACTION WITH DEVSEL# DECODE B AND TWO INITIAL WAIT STATES, MODE 2... 125 FIGURE 2-61: BURST READ TRANSACTION WITH DEVSEL# DECODE C AND TWO INITIAL WAIT STATES, MODE 2... 126 FIGURE 2-62: DWORD READ TRANSACTION WITH DEVSEL# DECODE B AND TWO INITIAL WAIT STATES, MODE 2... 126 FIGURE 2-63: DWORD READ TRANSACTION WITH DEVSEL# DECODE C AND TWO INITIAL WAIT STATES, MODE 2... 126 FIGURE 2-64: SPLIT COMPLETION ADDRESS... 132 FIGURE 2-65: COMPLETER ATTRIBUTE BIT ASSIGNMENTS... 134 FIGURE 2-66: SPLIT COMPLETION MESSAGE FORMAT... 138 FIGURE 2-67: INITIATOR TERMINATION OF A BURST TRANSACTION WITH FOUR OR MORE DATA PHASES... 142 FIGURE 2-68: INITIATOR TERMINATION OF A BURST TRANSACTION WITH THREE DATA PHASES... 146 11

FIGURE 2-69: INITIATOR TERMINATION OF A BURST TRANSACTION WITH TWO DATA PHASES... 146 FIGURE 2-70: INITIATOR TERMINATION OF A BURST TRANSACTION WITH ONE DATA PHASE... 146 FIGURE 2-71: MASTER-ABORT TERMINATION... 147 FIGURE 2-72: SINGLE DATA PHASE DISCONNECTION... 149 FIGURE 2-73: DISCONNECT AT NEXT ADB FOUR DATA PHASES FROM AN ADB... 152 FIGURE 2-74: DISCONNECT AT NEXT ADB ON ADB N... 153 FIGURE 2-75: DISCONNECT AT NEXT ADB WITH STARTING ADDRESS THREE DATA PHASES FROM AN ADB... 153 FIGURE 2-76: DISCONNECT AT NEXT ADB WITH STARTING ADDRESS TWO DATA PHASES FROM AN ADB... 154 FIGURE 2-77: DISCONNECT AT NEXT ADB WITH STARTING ADDRESS ONE DATA PHASE FROM AN ADB... 154 FIGURE 2-78: RETRY TERMINATION... 155 FIGURE 2-79: SPLIT RESPONSE TERMINATION FOR A READ TRANSACTION, MODE 1... 156 FIGURE 2-80: SPLIT RESPONSE TERMINATION FOR A DWORD WRITE TRANSACTION, MODE 1... 156 FIGURE 2-81: TARGET-ABORT ON FIRST DATA PHASE... 157 FIGURE 2-82: TARGET-ABORT AFTER DATA TRANSFER... 158 FIGURE 2-83: DUAL ADDRESS CYCLE 64-BIT MEMORY READ BURST TRANSACTION, PARITY-PROTECTED MODE 1... 161 FIGURE 2-84: DUAL ADDRESS CYCLE 64-BIT MEMORY READ BURST TRANSACTION, MODE 2... 161 FIGURE 2-85: 64-BIT INITIATOR READING FROM 32-BIT TARGET STARTING ON EVEN DWORD, PARITY-PROTECTED MODE 1... 165 FIGURE 2-86: 64-BIT INITIATOR READING FROM 32-BIT TARGET STARTING ON ODD DWORD, PARITY-PROTECTED MODE 1... 165 FIGURE 2-87: 64-BIT INITIATOR WRITING TO 32-BIT TARGET STARTING ON EVEN DWORD, PARITY-PROTECTED MODE 1... 166 FIGURE 2-88: 64-BIT INITIATOR WRITING TO 32-BIT TARGET STARTING ON ODD DWORD, PARITY-PROTECTED MODE 1... 166 FIGURE 2-89: 64-BIT INITIATOR WRITING TO 32-BIT TARGET STARTING ON ODD DWORD, DECODE A AND TWO INITIAL WAIT STATES, PARITY-PROTECTED MODE 1... 167 FIGURE 2-90: 64-BIT INITIATOR WRITING TO 32-BIT TARGET STARTING ON ODD DWORD, DECODE A AND FOUR INITIAL WAIT STATES, PARITY-PROTECTED MODE 1... 167 FIGURE 2-91: 64-BIT INITIATOR WRITING TO 32-BIT TARGET STARTING ON ODD DWORD, DECODE B, PARITY-PROTECTED MODE 1... 168 FIGURE 2-92: 64-BIT INITIATOR WRITING TO 32-BIT TARGET STARTING ON ODD DWORD, DECODE C AND TWO INITIAL WAIT STATES, PARITY-PROTECTED MODE 1... 168 FIGURE 2-93: 64-BIT INITIATOR READING FROM 32-BIT TARGET, DECODE B AND NO INITIAL WAIT STATES, -PROTECTED MODE 1... 169 FIGURE 2-94: 64-BIT INITIATOR BURST PUSH ADDRESSING A 32-BIT TARGET, DECODE B AND TWO INITIAL WAIT STATES, -PROTECTED MODE 1... 169 FIGURE 2-95: 64-BIT INITIATOR BURST PUSH ADDRESSING A 32-BIT TARGET, DECODE B AND FOUR INITIAL WAIT STATES, -PROTECTED MODE 1... 170 12

FIGURE 2-96: 64-BIT INITIATOR READING FROM 32-BIT TARGET, DECODE B AND NO INITIAL WAIT STATES, MODE 2... 170 FIGURE 2-97: 64-BIT INITIATOR BURST PUSH ADDRESSING A 32-BIT TARGET, DECODE B AND TWO INITIAL WAIT STATES, MODE 2... 171 FIGURE 2-98: 64-BIT INITIATOR BURST PUSH ADDRESSING A 32-BIT TARGET, DECODE B AND FOUR INITIAL WAIT STATES, MODE 2... 172 FIGURE 2-99: 64-BIT INITIATOR BURST PUSH ADDRESSING A 32-BIT TARGET, DECODE C AND TWO INITIAL WAIT STATES, MODE 2... 172 FIGURE 2-100: 64-BIT INITIATOR BURST PUSH ADDRESSING A 32-BIT TARGET, DIFFERENT DATA PHASE BOUNDARIES, MODE 2... 173 FIGURE 2-101: 64-BIT ADDRESS IN A 16-BIT TRANSACTION, DECODE B... 176 FIGURE 2-102: COMMON-CLOCK BURST WRITE WITH NO TARGET INITIAL WAIT STATES, 16-BIT MODE 2... 178 FIGURE 2-103: COMMON-CLOCK BURST WRITE WITH TWO TARGET INITIAL WAIT STATES, 16-BIT MODE 2... 179 FIGURE 2-104: SOURCE-SYNCHRONOUS (PCI-X 533) BURST WRITE WITH NO TARGET INITIAL WAIT STATES, 16-BIT MODE 2... 180 FIGURE 2-105: COMMON-CLOCK BURST READ WITH NO TARGET INITIAL WAIT STATES, 16-BIT MODE 2... 181 FIGURE 2-106: COMMON-CLOCK BURST READ WITH TWO TARGET INITIAL WAIT STATES, 16-BIT MODE 2... 182 FIGURE 2-107: DWORD WRITE WITH NO WAIT STATES AND DATA TRANSFER, 16-BIT MODE 2... 183 FIGURE 2-108: DWORD READ WITH NO WAIT STATES AND DATA TRANSFER, 16-BIT MODE 2... 183 FIGURE 2-109: SINGLE DATA PHASE DISCONNECT ON COMMON-CLOCK 16-BIT TRANSACTION... 184 FIGURE 2-110: SPLIT RESPONSE TO COMMON-CLOCK 16-BIT READ TRANSACTION... 184 FIGURE 2-111: SPLIT RESPONSE TO COMMON-CLOCK 16-BIT WRITE TRANSACTION... 185 FIGURE 2-112: DIM ADDRESS FORMAT, SINGLE ADDRESS CYCLE... 191 FIGURE 2-113: DIM ADDRESS FORMAT, DUAL ADDRESS CYCLE... 191 FIGURE 2-114: DIM ATTRIBUTE FORMAT... 193 FIGURE 3-1: A LOGIC BLOCK DIAGRAM FOR BYPASSING SOURCE SAMPLING... 198 FIGURE 4-1: INITIATING A TRANSACTION WHILE THE BUS IS PARKED, MODE 1... 202 FIGURE 4-2: BUS TURN-AROUND WHILE IDLE, NEW BUS OWNER (MODE 2)... 204 FIGURE 4-3: BUS TURN-AROUND WHILE IDLE, SAME BUS OWNER (MODE 2)... 205 FIGURE 4-4: BUS TURN-AROUND ON BUSY BUS, CASE 1 (MODE 2)... 206 FIGURE 4-5: BUS TURN-AROUND ON BUSY BUS, CASE 2 (MODE 2)... 207 FIGURE 4-6: BUS TURN-AROUND ON BUSY BUS, CASE 3 (MODE 2)... 207 FIGURE 4-7: BUS TURN-AROUND ON BUSY BUS, CASE 4 (MODE 2)... 208 FIGURE 4-8: INTERFACE LOW-POWER STATE (MODE 2)... 209 FIGURE 4-9: ENTERING LOW-POWER STATE BLOCKED BY NEW TRANSACTION, CASE 1 (MODE 2)... 210 FIGURE 4-10: ENTERING LOW-POWER STATE BLOCKED BY NEW TRANSACTION, CASE 2 (MODE 2)... 210 13

FIGURE 4-11: ENTERING LOW-POWER STATE BLOCKED BY NEW TRANSACTION, CASE 3 (MODE 2)... 211 FIGURE 4-12: ARBITRATION EXAMPLE, MODE 1... 217 FIGURE 5-1: BURST MEMORY WRITE TRANSACTION PARITY OPERATION... 223 FIGURE 5-2: BURST READ TRANSACTION PARITY OPERATION... 223 FIGURE 5-3: DWORD READ PARITY OPERATION, DECODE A AND NO INITIAL WAIT STATES... 224 FIGURE 5-4: DWORD READ PARITY OPERATION, DECODE B AND NO INITIAL WAIT STATES... 225 FIGURE 5-5: DWORD WRITE PARITY OPERATION, DECODE A AND NO INITIAL WAIT STATES... 225 FIGURE 5-6: DWORD WRITE PARITY OPERATION, DECODE B AND NO INITIAL WAIT STATES... 226 FIGURE 5-7: DWORD READ TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 1... 241 FIGURE 5-8: DWORD WRITE TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 1... 242 FIGURE 5-9: DWORD WRITE TRANSACTION OPERATION, DECODE B AND TWO INITIAL WAIT STATES, MODE 1... 242 FIGURE 5-10: 32-BIT BURST READ TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 1... 243 FIGURE 5-11: 32-BIT BURST PUSH TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 1... 243 FIGURE 5-12: 64-BIT BURST READ TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 1... 244 FIGURE 5-13: 64-BIT BURST READ TRANSACTION OPERATION, DECODE C AND TWO INITIAL WAIT STATES, MODE 1... 245 FIGURE 5-14: 64-BIT BURST PUSH TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 1... 246 FIGURE 5-15: DWORD READ TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 2... 246 FIGURE 5-16: DWORD WRITE TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 2... 247 FIGURE 5-17: DWORD WRITE TRANSACTION OPERATION, DECODE B AND TWO INITIAL WAIT STATES, MODE 2... 247 FIGURE 5-18: 32-BIT BURST READ TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 2... 248 FIGURE 5-19: 32-BIT COMMON-CLOCK BURST MEMORY WRITE TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 2... 248 FIGURE 5-20: 64-BIT BURST READ TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 2... 249 FIGURE 5-21: 64-BIT BURST READ TRANSACTION OPERATION, DECODE C AND TWO INITIAL WAIT STATES, MODE 2... 250 FIGURE 5-22: 64-BIT COMMON-CLOCK BURST MEMORY WRITE TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, MODE 2... 251 14

FIGURE 5-23: 32-BIT SOURCE-SYNCHRONOUS (PCI-X 533) TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES... 252 FIGURE 5-24: 32-BIT SOURCE-SYNCHRONOUS (PCI-X 533) TRANSACTION OPERATION, DECODE B AND TWO INITIAL WAIT STATES... 252 FIGURE 5-25: 64-BIT SOURCE-SYNCHRONOUS (PCI-X 533) TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES... 253 FIGURE 5-26: DWORD READ TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, 16-BIT MODE 2... 254 FIGURE 5-27: DWORD WRITE TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, 16-BIT MODE 2... 254 FIGURE 5-28: DWORD WRITE TRANSACTION OPERATION, DECODE B AND TWO INITIAL WAIT STATES, 16-BIT MODE 2... 255 FIGURE 5-29: COMMON-CLOCK BURST WRITE TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, 16-BIT MODE 2... 255 FIGURE 5-30: COMMON-CLOCK BURST WRITE TRANSACTION OPERATION WITH DECODE B AND TWO INITIAL WAIT STATES, 16-BIT MODE 2... 256 FIGURE 5-31: COMMON-CLOCK BURST READ TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, 16-BIT MODE 2... 256 FIGURE 5-32: COMMON-CLOCK BURST READ TRANSACTION OPERATION, DECODE B AND TWO INITIAL WAIT STATES, 16-BIT MODE 2... 257 FIGURE 5-33: SOURCE-SYNCHRONOUS (PCI-X 533) BURST WRITE TRANSACTION OPERATION, DECODE B AND NO INITIAL WAIT STATES, 16-BIT MODE 2... 257 FIGURE 5-34: SOURCE-SYNCHRONOUS (PCI-X 533) BURST WRITE TRANSACTION OPERATION, DECODE B AND TWO INITIAL WAIT STATES, 16-BIT MODE 2... 258 FIGURE 6-1: INTEROPERABILITY MATRIX FOR MODE AND I/O VOLTAGE KEYING... 269 FIGURE 6-2: PCI-X MODE LATCH, MODE 1 DEVICE... 275 FIGURE 7-1: PCI-X CAPABILITIES LIST ITEM FOR A TYPE 00H CONFIGURATION HEADER... 286 FIGURE 7-2: MODE 2 CONFIGURATION SPACE LAYOUT... 301 FIGURE 7-3: EXTENDED CAPABILITIES LIST ITEM FORMAT... 304 FIGURE 7-4: EXTENDED CAPABILITY HEADER... 304 FIGURE 8-1: STARTING AN EXCLUSIVE ACCESS WITH AN IMMEDIATE TRANSACTION, MODE 1... 334 FIGURE 8-2: STARTING AN EXCLUSIVE ACCESS WITH A SPLIT TRANSACTION, MODE 1. 335 FIGURE 8-3: CONTINUING AN EXCLUSIVE ACCESS, IMMEDIATE TRANSACTION, MODE 1... 336 FIGURE 8-4: ACCESSING A LOCKED DOWNSTREAM BRIDGE, MODE 1... 337 FIGURE 8-5: PCI-X CAPABILITIES LIST ITEM FOR A TYPE 01H CONFIGURATION HEADER... 340 FIGURE B-1: I 2 O STANDARD COMPONENTS... 384 FIGURE B-2: I 2 O PUSH MODEL... 386 FIGURE B-3: I 2 O PULL MODEL... 387 FIGURE E-1: CHECK/CORRECT LOGIC EXAMPLE... 401 15

Tables TABLE 1-1: CONVENTIONAL PCI AND PCI-X COMPARISON SUMMARY... 23 TABLE 1-2: SUPPORTED PCI-X MODES AND FEATURES... 23 TABLE 1-3: CONVENTIONAL PCI TRANSACTION PHASE DEFINITIONS... 40 TABLE 1-4: PCI-X TRANSACTION PHASE DEFINITIONS... 44 TABLE 1-5: COMPARISON OF BURST TRANSACTIONS AND DWORD TRANSACTIONS... 45 TABLE 2-1: NUMBER OF DATA PHASES BETWEEN TWO ADBS... 65 TABLE 2-2: BYTE LANE ASSIGNMENTS... 66 TABLE 2-3: ADDRESS ASSIGNMENT TO DATA LANES AND SUBPHASES, PCI-X 266... 67 TABLE 2-4: ADDRESS ASSIGNMENT TO DATA LANES AND SUBPHASES, PCI-X 533... 68 TABLE 2-5: AD[1::0] AND BYTE ENABLE ENCODINGS FOR I/O AND DWORD MEMORY TRANSACTIONS... 69 TABLE 2-6: STARTING ADDRESS AND BYTE ENABLE DEPENDENCIES FOR 32-BIT TRANSACTIONS USING THE MEMORY WRITE COMMAND... 69 TABLE 2-7: STARTING ADDRESS AND BYTE ENABLE DEPENDENCIES FOR 64-BIT TRANSACTIONS USING THE MEMORY WRITE COMMAND... 70 TABLE 2-8: PCI-X COMMAND ENCODING... 71 TABLE 2-9: BURST AND DWORD REQUESTER ATTRIBUTE FIELD DEFINITIONS... 73 TABLE 2-10: IDSEL GENERATION... 102 TABLE 2-11: DEVSEL# TIMING... 106 TABLE 2-12: TARGET INITIAL LATENCY... 114 TABLE 2-13: SPLIT COMPLETION ADDRESS FIELD DEFINITIONS... 133 TABLE 2-14: COMPLETER ATTRIBUTE FIELD DEFINITIONS... 135 TABLE 2-15: SPLIT COMPLETION MESSAGE FIELDS... 138 TABLE 2-16: WRITE COMPLETION MESSAGE INDEX (CLASS 0)... 139 TABLE 2-17: COMPLETER ERROR MESSAGES INDICES (CLASS 2)... 140 TABLE 2-18: DATA PHASES DEPENDENCE ON STARTING ADDRESS AND BUS WIDTH, MODE 1 AND COMMON-CLOCK MODE 2... 143 TABLE 2-19: DATA PHASES DEPENDENCE ON STARTING ADDRESS AND BUS WIDTH, SOURCE-SYNCHRONOUS PCI-X 266... 144 TABLE 2-20: DATA PHASES DEPENDENCE ON STARTING ADDRESS AND BUS WIDTH, SOURCE-SYNCHRONOUS PCI-X 533... 145 TABLE 2-21: TARGET DATA PHASE SIGNALING... 147 TABLE 2-22: 16-BIT BUS PIN SHARING... 174 TABLE 2-23: PCI-X WRITE COMPLETION LIMIT... 185 TABLE 2-24: DIM ADDRESS FIELD DEFINITIONS... 191 TABLE 2-25: DIM ATTRIBUTE FIELD DEFINITIONS... 193 TABLE 5-1: SEVEN-BIT GENERATION TABLE... 231 TABLE 5-2: EIGHT-BIT GENERATION TABLE EXTENSION... 232 TABLE 5-3: DATA PHASE ADDRESS SIGNATURE SELECTION... 235 TABLE 5-4: PHASE PROTECTION SIGNATURES... 236 TABLE 5-5: CHECK BIT SYNDROMES... 238 TABLE 5-6: REPORTING THE RECEIPT OF SPLIT COMPLETION ERROR MESSAGES... 265 TABLE 6-1: M66EN AND PCIXCAP ENCODING... 271 16

TABLE 6-2: PCI-X INITIALIZATION PATTERN... 272 TABLE 7-1: PCI-X COMMAND REGISTER... 286 TABLE 7-2: PCI-X STATUS REGISTER... 289 TABLE 7-3: CONTROL AND STATUS REGISTER... 296 TABLE 7-4: ENHANCED CONFIGURATION ACCESS ADDRESS MAPPING... 302 TABLE 7-5: EXTENDED CAPABILITY HEADER... 305 TABLE 8-1: CONVENTIONAL PCI TO PCI-X COMMAND TRANSLATION... 319 TABLE 8-2: PCI-X TO CONVENTIONAL PCI COMMAND TRANSLATION... 321 TABLE 8-3: TRANSACTIONS ORDERING AND DEADLOCK-AVOIDANCE RULES... 325 TABLE 8-4: PCI-X SECONDARY STATUS REGISTER... 342 TABLE 8-5: PCI-X BRIDGE STATUS REGISTER... 346 TABLE 8-6: UPSTREAM SPLIT TRANSACTION REGISTER... 350 TABLE 8-7: DOWNSTREAM SPLIT TRANSACTION REGISTER... 352 TABLE 8-8: PCI-X BRIDGE CONTROL AND STATUS REGISTER... 353 TABLE 8-9: BRIDGE DATA-PHASE FORWARDING ACTIONS, PARITY TO PARITY... 365 TABLE 8-10: BRIDGE DATA-PHASE FORWARDING ACTIONS, TO... 366 TABLE 8-11: BRIDGE DATA-PHASE FORWARDING ACTIONS, PARITY TO... 368 TABLE 8-12: BRIDGE DATA-PHASE FORWARDING ACTIONS, TO PARITY... 370 TABLE 8-13: PCI-X BRIDGE ERROR MESSAGES INDICES (CLASS 1)... 372 TABLE A-1: CONVENTIONAL PCI VS. PCI-X PROTOCOL COMPARISON... 375 TABLE E-1: CHECK BIT SYNDROMES IN COMBINED SIGNATURES... 399 TABLE E-2: SYNDROMES FOR SINGLE-PIN DOUBLE-BIT ERRORS ON THE 16-BIT BUS... 400 TABLE E-3: SUMMARY OF REQUIREMENTS... 403 TABLE E-4: FOR A 32-BIT INITIATOR 128-BYTE MEMORY WRITE BLOCK TO A 32-BIT TARGET... 404 TABLE E-5: FOR A 32-BIT INITIATOR 128-BYTE MEMORY WRITE TO A 32-BIT TARGET... 407 TABLE E-6: FOR A 32-BIT INITIATOR DWORD I/O WRITE TO A 32-BIT TARGET.. 407 TABLE E-7: FOR A 64-BIT INITIATOR 512-BYTE MEMORY WRITE BLOCK TO A 64-BIT TARGET... 408 TABLE E-8: FOR A 64-BIT INITIATOR 128-BYTE MEMORY WRITE BLOCK TO A 64-BIT TARGET... 409 TABLE E-9: FOR A 64-BIT INITIATOR 128-BYTE MEMORY WRITE TO A 64-BIT TARGET... 410 TABLE E-10: FOR A 16-BIT BUS 64-BYTE MEMORY WRITE BLOCK... 411 TABLE E-11: FOR A 16-BIT BUS 32-BYTE MEMORY WRITE WITH 64-BIT ADDRESSING... 412 17

18

Preface Since the introduction of revision 1.0 of the PCI-X Addendum to the PCI Local Bus Specification in 1999, peripheral data rates have continued to grow. Recognizing the need to keep the PCI specifications (the most popular industry standard interface ever developed) ahead of the market need for these peripherals, the PCI-SIG formed a working group in 2001 to double and quadruple the data rates supported by the PCI-X definition. This document, the PCI-X Protocol Addendum to the PCI Local Bus Specification, Revision 2.0a (PCI-X PT 2.0a), and the PCI-X Electrical and Mechanical Addendum to the PCI Local Bus Specification, Revision 2.0 (PCI-X EM 2.0) are the result of that effort. PCI-X PT 2.0a and PCI-X EM 2.0 are collectively referred to as PCI-X 2.0 and together replace the PCI-X Addendum to the PCI Local Bus Specification, Revision 1.0b (PCI-X 1.0b). To achieve these higher data rates, PCI-X 2.0 adds a source-synchronous clocking mode for the highest-performance burst transactions that enables transfer rates in excess of 4 GB/s. It also defines: 1.5V signaling levels for faster signaling and improved signal integrity characteristics Error correcting codes () for improved error immunity Expanded Configuration Space address range of 4096 bytes A low-pin-count 16-bit interface for embedded applications A new device-id messaging transaction for peer-to-peer communication Following the well-established tradition of all PCI specifications, PCI-X 2.0 stresses backward compatibility. Devices and cards compliant with PCI-X 1.0b are fully supported in PCI-X 2.0, in what is defined as Mode 1. The higher transfer rates in PCI-X 2.0 are defined as Mode 2. PCI-X devices that support both Mode 1 and Mode 2 are completely interoperable with devices designed to support the previous revision of the PCI-X definition and 33 MHz, 3.3V conventional PCI devices. They optionally support the 66 MHz conventional PCI mode. support, the expanded Configuration Space, and the 16-bit interface are required for Mode 2 devices. Forwarding device ID messages is required for PCI-X Mode 2 bridges. support and device ID messaging are optional for Mode 1 devices. The new features in PCI-X 2.0 are defined to minimize the changes required when migrating from a PCI-X 1.0b design. Most requirements of PCI-X 1.0b remain unchanged in PCI-X 2.0. Therefore, the new requirements for the new modes defined in PCI-X 2.0 are distributed throughout PCI-X PT 2.0a and PCI-X EM 2.0 in the locations where they make the most sense. The result is a single document that defines the protocol requirements for PCI-X devices ranging from 266 MB/s (32-bit, 66 megatransfers/s) to more than 4 GB/s (64-bit, 533 megatransfers/s). A separate document defines the electrical and mechanical requirements for the same range of devices. 19

Future Changes Following publication of PCI-X PT 2.0a, there may be future approved errata, clarification, and/or modifications to this specification, prior to the issuance of another formal revision. To assure designs meet the latest level requirements, designers of PCI-X devices must refer to the PCI-SIG web site at http://www.pcisig.com for the approved changes. 20

1 1. Introduction The PCI-X Protocol Addendum to the PCI Local Bus Specification, Revision 2.0 (PCI-X PT 2.0a), together with the PCI-X Electrical and Mechanical Addendum to the PCI Local Bus Specification, Revision 2.0 (PCI-X EM 2.0), define enhancements to the PCI Local Bus Specification, Revision 2.3 (PCI 2.3), the PCI to PCI Bridge Architecture Specification, Revision 1.1 (PCI Bridge 1.1), the PCI Power Management Interface Specification, Revision 1.1 (PCI PM 1.1), and the PCI Hot-Plug Specification, Revision 1.1 (PCI HP 1.1), which are the latest versions of these specifications at the time of release of this document. Contact the PCI-SIG for any later revisions. PCI-X PT 2.0a and PCI-X EM 2.0 are collectively referred to as PCI-X 2.0 and together replace the PCI-X Addendum to the PCI Local Bus Specification, Revision 1.0b (PCI-X 1.0b). The PCI-X definition introduces several major enhancements that enable faster and more efficient data transfers: 1. Higher clock frequencies up to 133 MHz 1. 2. Signaling protocol changes to enable registered outputs and inputs, that is, device outputs that are clocked directly out of a register and device inputs that are clocked directly into a register. The protocol is restricted such that devices have two clocks to respond to any input changes. 3. New information passed with each transaction that enables more efficient buffer management schemes. Each transaction in a Sequence (see the definition in Section 1.2) identifies the total number of bytes remaining to be read or written. If a transaction is disconnected, the new transaction that continues the Sequence contains an updated remaining byte count. Each transaction includes the identity of the initiator (bus number, device number, and function number) and the transaction sequence (or thread ) to which it belongs (Tag). Additional information about transaction ordering and cacheability requirements. 4. Restricted wait state and disconnection rules optimized for more efficient use of the bus and memory resources. Initiators are not permitted to insert wait states. 1 This specification follows the precedent of PCI 2.3 by abbreviating clock frequency notation. For example, 133 1/3 MHz (the actual maximum frequency for PCI-X devices) is written 133 MHz, 66 2/3 MHz is written 66 MHz and 33 1/3 MHz is written 33 MHz. Actual clock frequencies are specified in Section 2.1.2.4.1, Clock Specification, in PCI-X EM 2.0. 21

Targets are not permitted to insert wait states after the initial data phase. Both initiators and targets are permitted to end a burst transaction only on naturally aligned 128-byte boundaries. This encourages longer bursts and enables more efficient use of cacheline-based resources such as the host bus and main memory. Targets are also permitted to disconnect transactions after only a single data phase in address ranges where longer transactions are not necessary. 5. Delayed Transactions in conventional PCI replaced by Split Transactions in PCI-X. All transactions except memory write transactions must be completed immediately or they must be completed using Split Transaction protocol. In Split Transaction protocol, the target terminates a transaction by signaling Split Response, executes the command, and initiates its own Split Completion transaction to send the data or a completion message back to the original initiator. 6. A wider range of error recovery implementations for PCI-X devices that reduce system intervention on uncorrectable data errors. PCI-X 2.0 defines two modes of operation. Mode 1 is the mode of operation defined in previous versions of the PCI-X definition. The following features defined in PCI-X 2.0 are required for Mode 2 devices and optional for Mode 1 devices: 1. An error correcting code () replaces parity. 2. The fastest target device decode speed in mode is one clock slower than parity mode. This allows time for the target to check and correct errors in the transaction address before responding. 3. A previously reserved transaction command is defined to be the Device ID Message command. 4. A new clock jitter class is added that reduces the absolute minimum clock period to allow for jitter. 5. Interrupt mask and status bits defined in PCI 2.3. Mode 2 also includes the following features: 1. Almost all of the Mode 1 control signal and transaction phase rules have been kept the same in Mode 2 to minimize design changes. 2. The initiator of transactions that use the highest performance commands drives data at two or four times the common clock frequency. These cases use source-synchronous clocking techniques for transferring the data, rather than capturing data with the common clock. 3. The Configuration Space addresses are extended from eight to 12 bits, enabling the addressing of 4096 bytes for each function of each device. 4. A low-pin-count 16-bit interface for embedded applications. 5. Electrical and logical changes have been made to improve the signal integrity and reduce electrical noise. Signaling voltages are lowered to 1.5V for the source-synchronous 22

signals. (The common-clock control signals remain at 3.3V.) The system switches the V I/O supply voltage between 3.3V or 1.5V depending upon whether the bus is operating in Mode 1 or Mode 2 respectively. Input buffers for the source-synchronous signals include terminating resistors. 6. The signal terminating voltage for the source-synchronous signals is centered around the receiver threshold, and thus requires that receivers never be enabled when no driver is driving the signal. The lower buses are generally driven all the time, except during oneclock bus turn-around. Table 1-1 compares maximum transfer rates and signaling levels among all the conventional and PCI-X modes. Table 1-1: Conventional PCI and PCI-X Comparison Summary Maximum Transfer Rate (MB/s) Mode Signaling Level 64-Bit Bus 32-Bit Bus 16-Bit Bus Conventional PCI 33 (ref) 5V or 3.3V 266 133 na Conventional PCI 66 (ref) 3.3V 533 266 na PCI-X 66 3.3V 533 266 na PCI-X 133 3.3V 1066 533 na PCI-X 266 1.5V and 3.3V 2133 1066 533 PCI-X 533 1.5V and 3.3V 4266 2133 1066 Table 1-2 shows the supported combinations of modes and features for PCI-X. Table 1-2: Supported PCI-X Modes and Features Feature PCI-X Mode 1 PCI-X Mode 2 Device types PCI-X 66 PCI-X 133 PCI-X 266 PCI-X 533 64 bit optional Bus width 64 bit optional 32-bit: Required for add-in card applications. 32-bit required Optional for embedded applications 16-bit required Interface Signaling 3.3V 1.5V and 3.3V Error protection Parity required optional required Data capture Common-clock Common-clock and source-synchronous 12-bit Configuration Space address Not supported Required Device ID messages Optional Required 23

PCI-X requirements are defined in many cases to be the same or similar to their corresponding conventional PCI requirements. This simplifies the task of converting conventional designs to PCI-X and of making PCI-X devices that work in conventional environments. In most cases, this document does not repeat specifications that remain unchanged from PCI 2.3, PCI Bridge 1.1, PCI PM 1.1, and PCI HP 1.1. Any requirement not specified to be different for PCI-X devices remains the same as specified in these other specifications. The following PCI-X features are some of the features that are the same as conventional PCI: 1. Devices are required to support a 32-bit data bus. They optionally support a 64-bit data bus. 2. Address and data are multiplexed on the same bus. 3. 64- and 32-bit transactions have one or two address phases. 4. Transactions have one or more data phases. 5. Devices decode address and command and assert DEVSEL# to claim a transaction. 6. Add-in card mechanical specification, except a new identification requirement (see Section 3.2, Identification Requirements, in PCI-X EM 2.0). PCI-X Mode 1 add-in cards are keyed for 3.3V or Universal signaling. PCI-X Mode 2 add-in cards are keyed exclusively for 3.3V signaling. 7. Maximum power consumption for add-in cards. 8. PCI hot-plug architecture and hot-insertion and hot-removal sequences. The following PCI-X features have been kept similar to conventional PCI: 1. Signaling protocol on FRAME#, IRDY#, DEVSEL#, TRDY#, and STOP#. 2. Data phases complete each time IRDY# and TRDY# are both asserted. Some additional target data-phase signaling is defined for PCI-X. 3. Transaction ordering and passing rules for bridges (Split Transactions in PCI-X replace Delayed Transactions in conventional PCI). 4. In PCI-X Mode 1, electrical signaling voltage levels are the same as conventional 3.3V signaling, except V il (max) is slightly higher in PCI-X mode to provide additional noise margin. 5. Device and add-in card electrical specification ranges are generally narrower for PCI-X devices. 6. In PCI-X Mode 1 and PCI-X Mode 2 common-clock transfers, there is a single clock signal for all devices and transactions. The bus changes state and data transfers on the rising edge of the clock. In PCI-X Mode 2 source-synchronous transfers, the device driving data also drives strobes used for latching the data. 7. In parity mode, signal names and add-in card connector pin-out remains unchanged (except two new pins, PCIXCAP and MODE2). In mode, new pins are added to support on each phase of the transaction. 24

8. Power supply voltages remain unchanged, except V I/O switches to 1.5V in PCI-X Mode 2. 1.1. Documentation Conventions In addition to the documentation conventions established in PCI 2.3, the following conventions are used in this document: Capitalization Names of transaction commands and target termination methods are presented with the first letter capitalized and the rest lower case, e.g., Memory Read Block, Memory Write Block, Retry, Target-Abort, and Single Data Phase Disconnect. As in PCI 2.3, register names and the names of fields and bits in registers and attributes are presented with the first letter capitalized and the rest lower case, e.g., PCI-X Status register, PCI-X Command register, Byte Count field, Bus Number field, and No Snoop attribute bit. Some other terms are capitalized to distinguish their definition in the context of this document from their common English meaning. These terms are listed in Section 1.2. Words not capitalized have their common English meaning. When terms such as memory write or memory read appear completely in lower case, they include all transactions of that type. For example, transactions using the Memory Write, Memory Write Block, and Alias to Memory Write Block commands are all included by the phrase, memory write transactions. Numbers and number bases Buses Hexadecimal numbers are written with a lower case h suffix, e.g., FFFFh and 80h. Hexadecimal numbers larger than four digits are represented with a space dividing each group of four digits, as in 1E FFFF FFFFh. Binary numbers are written with a lower case b suffix, e.g., 1001b and 10b. Binary numbers larger than four digits are represented with a space dividing each group of four digits, as in 1000 0101 0010b. All other numbers are decimal. As in PCI 2.3, collections of signals that are collectively driven and received are assigned the same signal name with numbers in brackets to indicate the bit or bits affected, e.g., AD[31::00], C/BE[7::4]#, and AD[2]. 25

Reference information Device types Clock numbering Reference information is provided in various places to assist the reader and does not represent a requirement of this document. Such references are indicated by the abbreviation (ref). For example, in some places a clock that is specified to have a minimum period of 15 ns also includes the reference information maximum clock frequency of 66 MHz (ref). Requirements of other specifications also appear in various places throughout this document and are marked as reference information. Every effort has been made to guarantee that this information accurately reflects the referenced document. However, in case of discrepancy, the original document takes precedence. As in conventional PCI, PCI-X devices are required to operate up to a maximum frequency (down to a minimum clock period). The system is permitted to operate the bus at a lower frequency to compensate for additional bus loading. This document refers to the type of the device as either conventional or PCI-X and the appropriate maximum data transfer rate. Conventional PCI 33 Conventional PCI 66 PCI-X 66 PCI-X 133 PCI-X 266 PCI-X 533 In all cases, the actual operating clock frequency is between the minimum and maximum specified for that device. As in PCI 2.3, this document designates the clock that a particular event occurs based on its appearance on the bus. For example, if as a result of a particular clock edge, N, a device changes its output state to begin asserting a signal, that device is said to assert the signal on clock N+1 or the signal is said to be asserted on clock N+1. In PCI-X Mode 2, each source-synchronous data phase contains multiple subphases. For these data phases, a device is said to drive data between clocks N and N+1 even if the actual output delay is such that one or more subphases are delayed past clock N+1. 26