PCI EXPRESS BASE SPECIFICATION, REV. 4.0 VERSION 0.7
5
Contents
OBJECTIVE OF THE SPECIFICATION ............................................................................... 43
DOCUMENT ORGANIZATION.............................................................................................. 43
DOCUMENTATION CONVENTIONS ................................................................................... 43
TERMS AND ACRONYMS ...................................................................................................... 44
REFERENCE DOCUMENTS ................................................................................................... 55
1 INTRODUCTION............................................................................................................... 56
1.1 A THIRD GENERATION I/O INTERCONNECT ................................................................... 56
1.2 PCI EXPRESS LINK ......................................................................................................... 59
1.3 PCI EXPRESS FABRIC TOPOLOGY .................................................................................. 60
1.3.1 Root Complex ............................................................................................................ 60
1.3.2 Endpoints .................................................................................................................. 61
1.3.3 Switch ........................................................................................................................ 64
1.3.4 Root Complex Event Collector .................................................................................. 65
1.3.5 PCI Express to PCI/PCI-X Bridge ............................................................................ 65
1.4 PCI EXPRESS FABRIC TOPOLOGY CONFIGURATION ....................................................... 65
1.5 PCI EXPRESS LAYERING OVERVIEW .............................................................................. 66
1.5.1 Transaction Layer ..................................................................................................... 67
1.5.2 Data Link Layer ........................................................................................................ 67
1.5.3 Physical Layer .......................................................................................................... 68
1.5.4 Layer Functions and Services ................................................................................... 68
2 TRANSACTION LAYER SPECIFICATION ................................................................. 72
2.1 TRANSACTION LAYER OVERVIEW.................................................................................. 72
2.1.1 Address Spaces, Transaction Types, and Usage ....................................................... 73
2.1.2 Packet Format Overview .......................................................................................... 75
2.2 TRANSACTION LAYER PROTOCOL - PACKET DEFINITION ............................................... 77
2.2.1 Common Packet Header Fields ................................................................................ 77
2.2.2 TLPs with Data Payloads - Rules ............................................................................. 80
2.2.3 TLP Digest Rules ...................................................................................................... 84
2.2.4 Routing and Addressing Rules .................................................................................. 84
2.2.5 First/Last DW Byte Enables Rules ............................................................................ 88
2.2.6 Transaction Descriptor ............................................................................................. 91
2.2.7 Memory, I/O, and Configuration Request Rules ..................................................... 101
2.2.8 Message Request Rules ........................................................................................... 109
2.2.9 Completion Rules .................................................................................................... 130
2.2.10 TLP Prefix Rules ................................................................................................. 134
2.3 HANDLING OF RECEIVED TLPS .................................................................................... 139
2.3.1 Request Handling Rules .......................................................................................... 142
2.3.2 Completion Handling Rules .................................................................................... 154
2.4 TRANSACTION ORDERING ............................................................................................ 158
2.4.1 Transaction Ordering Rules ................................................................................... 158
