PCI Express
®
Base Specification
Revision 2
3.0
Version 0.5
December 20
September 12, 2006 2008
2
Revision Revision History DATE
1.0 Initial release. 07/22/2002
1.0a Incorporated Errata C1-C66 and E1-E4.17. 04/15/2003
1.1 Incorporated approved Errata and ECNs. 03/28/2005
2.0 Added 5.0 GT/s data rate and incorporated approved Errata
and ECNs.
12/20/2006
3.0, ver. 0.3 First PCI-SIG membership review. 05/22/2008
3.0, ver. 0.5 Incorporated approved errata and ECNs and updated Chapter
4,
09/12/2008
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®
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Questions regarding the PCI Express Base Specification or membership in PCI-SIG may be
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DISCLAIMER
This PCI Express Base Specification is provided “as is” with no warranties whatsoever, including
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liability for infringement of proprietary rights, relating to use of information in this specification.
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Copyright © 2002-2006 2008 PCI-SIG
PCI EXPRESS BASE SPECIFICATION, REV. 23.0, VER. 0.5
3
Contents
OBJECTIVE OF THE SPECIFICATION............................................................................... 23
DOCUMENT ORGANIZATION.............................................................................................. 23
DOCUMENTATION CONVENTIONS................................................................................... 24
TERMS AND ACRONYMS...................................................................................................... 25
REFERENCE DOCUMENTS................................................................................................... 32
1. INTRODUCTION............................................................................................................... 33
1.1. A THIRD GENERATION I/O INTERCONNECT ................................................................... 33
1.2. PCI EXPRESS LINK......................................................................................................... 35
1.3. PCI EXPRESS FABRIC TOPOLOGY .................................................................................. 37
1.3.1. Root Complex........................................................................................................ 37
1.3.2. Endpoints .............................................................................................................. 38
1.3.3. Switch.................................................................................................................... 41
1.3.4. Root Complex Event Collector.............................................................................. 42
1.3.5. PCI Express to PCI/PCI-X Bridge........................................................................ 42
1.4. PCI EXPRESS FABRIC TOPOLOGY CONFIGURATION....................................................... 42
1.5. PCI EXPRESS LAYERING OVERVIEW.............................................................................. 43
1.5.1. Transaction Layer................................................................................................. 44
1.5.2. Data Link Layer.................................................................................................... 44
1.5.3. Physical Layer ...................................................................................................... 45
1.5.4. Layer Functions and Services............................................................................... 45
2. TRANSACTION LAYER SPECIFICATION ................................................................. 49
2.1. T
RANSACTION LAYER OVERVIEW.................................................................................. 49
2.1.1. Address Spaces, Transaction Types, and Usage................................................... 50
2.1.2. Packet Format Overview ...................................................................................... 52
2.2. TRANSACTION LAYER PROTOCOL - PACKET DEFINITION............................................... 53
2.2.1. Common Packet Header Fields ............................................................................ 53
2.2.2. TLPs with Data Payloads - Rules......................................................................... 56
2.2.3. TLP Digest Rules .................................................................................................. 60
2.2.4. Routing and Addressing Rules.............................................................................. 60
2.2.5. First/Last DW Byte Enables Rules........................................................................ 64
2.2.6. Transaction Descriptor......................................................................................... 67
2.2.7. Memory, I/O, and Configuration Request Rules................................................... 72
2.2.8. Message Request Rules......................................................................................... 77
2.2.9. Completion Rules.................................................................................................. 91
2.3. H
ANDLING OF RECEIVED TLPS...................................................................................... 94
2.3.1. Request Handling Rules........................................................................................ 97
PCI EXPRESS BASE SPECIFICATION, REV. 23.0, VER. 0.5
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2.3.2. Completion Handling Rules................................................................................ 110
2.4. TRANSACTION ORDERING............................................................................................ 112
2.4.1. Transaction Ordering Rules ............................................................................... 112
2.4.2. Update Ordering and Granularity Observed by a Read Transaction................ 118
2.4.3. Update Ordering and Granularity Provided by a Write Transaction................ 119
2.5. VIRTUAL CHANNEL (VC) MECHANISM........................................................................ 119
2.5.1. Virtual Channel Identification (VC ID).............................................................. 121
2.5.2. TC to VC Mapping.............................................................................................. 122
2.5.3. VC and TC Rules................................................................................................. 123
2.6. ORDERING AND RECEIVE BUFFER FLOW CONTROL ..................................................... 124
2.6.1. Flow Control Rules............................................................................................. 125
2.7. DATA INTEGRITY ......................................................................................................... 135
2.7.1. ECRC Rules ........................................................................................................ 136
2.7.2. Error Forwarding............................................................................................... 140
2.8. COMPLETION TIMEOUT MECHANISM ........................................................................... 142
2.9. LINK STATUS DEPENDENCIES ...................................................................................... 143
2.9.1. Transaction Layer Behavior in DL_Down Status............................................... 143
2.9.2. Transaction Layer Behavior in DL_Up Status ................................................... 144
3. DATA LINK LAYER SPECIFICATION ...................................................................... 145
3.1. DATA LINK LAYER OVERVIEW .................................................................................... 145
3.2. DATA LINK CONTROL AND MANAGEMENT STATE MACHINE ...................................... 147
3.2.1. Data Link Control and Management State Machine Rules ................................ 148
3.3. FLOW CONTROL INITIALIZATION PROTOCOL ............................................................... 150
3.3.1. Flow Control Initialization State Machine Rules ............................................... 150
3.4. DATA LINK LAYER PACKETS (DLLPS)........................................................................ 154
3.4.1. Data Link Layer Packet Rules ............................................................................ 154
3.5. DATA INTEGRITY ......................................................................................................... 159
3.5.1. Introduction......................................................................................................... 159
3.5.2. LCRC, Sequence Number, and Retry Management (TLP Transmitter).............. 159
3.5.3. LCRC and Sequence Number (TLP Receiver).................................................... 171
4. PHYSICAL LAYER SPECIFICATION........................................................................ 179
4.1. INTRODUCTION ............................................................................................................ 179
4.2. L
OGICAL SUB-BLOCK................................................................................................... 179
4.2.1. Encoding for 2.5 GT/s and 5 GT/s Data Rates................................................... 180
4.2.2. Encoding for 8GT/s and Higher Data Rates....................................................... 188
4.2.3. <Placeholder>.................................................................................................... 204
4.2.4. Link Initialization and Training.......................................................................... 204
4.2.5. Link Training and Status State Machine (LTSSM) Descriptions........................ 219
4.2.6. Link Training and Status State Rules.................................................................. 222
4.2.7. Clock Tolerance Compensation.......................................................................... 269
4.2.8. Compliance Pattern ............................................................................................ 272
4.2.9. Modified Compliance Pattern............................................................................. 273
4.3. E
LECTRICAL SUB-BLOCK ............................................................................................. 275
4.3.1. Maintaining Backwards Compatibility............................................................... 275
4.3.2. Jitter Budgeting and Measurement..................................................................... 277
PCI EXPRESS BASE SPECIFICATION, REV. 23.0, VER. 0.5
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4.3.3. Transmitter Specification.................................................................................... 278
4.3.4. Receiver Specification......................................................................................... 293
4.3.5. Transmitter and Receiver DC Specifications...................................................... 307
4.3.6. Channel Specifications........................................................................................ 312
4.3.7. Reference Clock Specifications........................................................................... 319
4.4. 8.0G ELECTRICAL SPECIFICATION ............................................................................... 327
4.4.1. 8.0G Transmitter Specifications ......................................................................... 327
4.4.2. 8.0G Receiver Specifications .............................................................................. 335
4.4.3. Channel Compliance Testing.............................................................................. 345
4.4.4. Refclk Parameters for 8.0G ................................................................................ 352
5. POWER MANAGEMENT .............................................................................................. 357
5.1. OVERVIEW ................................................................................................................... 357
5.1.1. Statement of Requirements.................................................................................. 358
5.2. L
INK STATE POWER MANAGEMENT............................................................................. 358
5.3. PCI-PM
SOFTWARE COMPATIBLE MECHANISMS......................................................... 363
5.3.1. Device Power Management States (D-States) of a Function.............................. 363
5.3.2. PM Software Control of the Link Power Management State.............................. 367
5.3.3. Power Management Event Mechanisms............................................................. 373
5.4. NATIVE PCI EXPRESS POWER MANAGEMENT MECHANISMS....................................... 380
5.4.1. Active State Power Management (ASPM) .......................................................... 380
5.5. AUXILIARY POWER SUPPORT....................................................................................... 396
5.5.1. Auxiliary Power Enabling................................................................................... 396
5.6. POWER MANAGEMENT SYSTEM MESSAGES AND DLLPS............................................. 397
6. SYSTEM ARCHITECTURE .......................................................................................... 399
6.1. INTERRUPT AND PME SUPPORT ................................................................................... 399
6.1.1. Rationale for PCI Express Interrupt Model........................................................ 399
6.1.2. PCI Compatible INTx Emulation........................................................................ 400
6.1.3. INTx Emulation Software Model ........................................................................ 400
6.1.4. Message Signaled Interrupt (MSI/MSI-X) Support............................................. 400
6.1.5. PME Support....................................................................................................... 402
6.1.6. Native PME Software Model .............................................................................. 402
6.1.7. Legacy PME Software Model ............................................................................. 403
6.1.8. Operating System Power Management Notification........................................... 403
6.1.9. PME Routing Between PCI Express and PCI Hierarchies ................................ 403
6.2. E
RROR SIGNALING AND LOGGING................................................................................ 404
6.2.1. Scope................................................................................................................... 404
6.2.2. Error Classification............................................................................................ 404
6.2.3. Error Signaling................................................................................................... 406
6.2.4. Error Logging..................................................................................................... 413
6.2.5. Sequence of Device Error Signaling and Logging Operations .......................... 417
6.2.6. Error Message Controls ..................................................................................... 420
6.2.7. Error Listing and Rules ...................................................................................... 421
6.2.8. Virtual PCI Bridge Error Handling.................................................................... 426
6.2.9. Internal Errors.................................................................................................... 427
6.3. V
IRTUAL CHANNEL SUPPORT ...................................................................................... 428
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