About This Book
The MindShare Architecture Series
Cautionary Note
This Book Assumes PCI Background Knowledge
Specifications This Book Is Based On
Organization of This Book
Who This Book Is For
Prerequisite Knowledge
Documentation Conventions
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Part l: Basic Concepts
Chapter 1: PCI Needed Improvement
Wait States Yield Poor Performance
Relatively Slow Clock Speed
Transfer Size Unknown
PCI Delayed Transactions Are Inefficient
Snoops Hurt Performance
Processor(s)
Latency Timer Use Not Optimized in PCI
Data Phase Parity Error Recovery Usually Not Possible
No Indication of Device Width
MSI Feature Optional in PCI Environment
Power Management Optional
Configuration Software Constrained by 32-Bit Memory BARs
Stepping Yields Poor Performance
Chapter 2: PCI-X Improves on PCI
PCI-X Is Backward-Compatible With PCI
PCI-X Is More System-Centric Than PCI
Higher Clock Speeds Possible
Wait States Eliminated
Data Transferred in Blocks
Disconnecting on Block Boundaries
Latency Timer Usage
Requester and Completer
Transfer Size Specified
Requester ID and Transaction ID Are Specified
Split Transactions Replace Delayed Transactions
Dynamic Traffic Analysis and Load Tuning
Data Phase Parity Error Recovery
64-Bit Connection Indication
MSI Feature Mandatory
Power Management Mandatory for Add-In Devices
Snoops Can Be Eliminated
Memory BARS Must Be 64-Bit Width
Bus Masters That Access Memory Must Support DAC Command
Stepping Eliminated
Fast Back-to-Back Transactions Eliminated
Chapter 3: Lowest Common Denominator Defines Mode
Bus Protocol/Speed = Lowest Common Denominator
Discovering a PCI-X Bus
Discovering PCI Devices on a PCLX Bus
Some Example Systems
Systems Supporting Both PCI-X and PCI Environments
Chapter 4: Device Types and Bus Initialization
All Devices Support 33MHz PCI
All PCI-X Devices Support 66MHz PCI-X Mode
PCIXCAP Indicates Protocol/Frequency Required
Device Not Permitted to Use PCIXCAP as Input or Output
Bridge's Interpretation of M66EN and PCIXCAP
Maximum Reliable Speed Verified by Design and Testing
Supplying PCI-X Devices With Protocol and Speed
Why Bus Must Be Idle When Init Pattern Driven
Upon Receipt of Pattern. Device Initializes Itself
Init Pattern Setup and Hold Time
Reassertion of RST# Necessitates Redelivery of Pattern
Bridge Must Support Interfaces in Different Modes
Hot-Plug PCI-X Bus Initialization
Placing Device in Low-Power Mode Requires Quiesce
Chapter 5: PCI-X Is a Registered Bus
PCI-X Is a Low-Voltage Swing (LVS) Bus
Introduction to the Registered Nature of the Bus
Address/Command Decode Example
Data Read Example
Chapter 6: Intro to Commands
Commands Fall Into Three Categories
Command Encoding
Dword Commands
Burst Commands
Dual-Address Cycle (DAC) Command
Chapter 7: Intro to Transaction Phases
The PCI Transaction Phases
The PCLX Transaction Phases
Chapter 8: Intro to Transaction Termination
Introduction
Initiator Termination of Transaction
Early Target Termination of Transaction
Bridge Handling of Memory Writes
Bridge Handling of Transactions Other Than Memory Writes
Chapter 9: Intro to Split and Immediate Transactions
Definition of Requester and Completer
Definition of a Sequence
Definition of Requester ID, Tag, and Sequence ID
How Does a Device Know Its Requester ID?
Immediate Transaction
Memory Writes Are Posted
Split Transactions
Part 2: Transaction Protocol
Chapter 10: Bus Arbitration
Stepping Not Permitted
Request and Grant Signals Are Registered
Example Arbitration
Device Design Rules
Arbiter Design Rules
Bus Parking
How the Initiator Deals With Preemption
Chapter 11: Detailed Command Description
Dword Commands,
Burst Commands
Dual-Address Cycle (DAC) Command
Chapter 12: Latency Rules
Initiator Latency Rules
Target Latency Rules
Maximum Completion Time
Chapter 13: The Address. Attribute and Response Phases
All Transactions Begin With Address and Attribute Phases
Memory Transaction May Have Two Address Phases
Attributes Always Delivered on Lower Half of Bus
Address/Attribute Format Depends on Command Type
Memory Burst Format
Dword Command (other than Config) Format
Configuration Command Format
Split Completion Command Format
The Response Phase: Connecting With the Target
Chapter 14: Dword Transactions
General
General Format of Timing Diagram Descriptions
IO Read and Memory Read Dword
IO Write
Configuration Read and Write Transactions
Interrupt Acknowledge Command
Special Cycle Command
Chapter 15: Burst Transactions
Introduction
General Format of Timing Diagram Descriptions
Memory Read Block Transaction
Memory Write Block Transaction
Memory Write Transaction
Split Completion Transaction
Alias To Memory Block Commands
Chapter 16: Transaction Terminations
General Format of Timing Diagram Descriptions
Termination by the Initiator
Termination By the Target
Chapter 17: Split Completion Messages
Purpose of Split Completion Messages
SCM Always Terminates a Sequence
Upon Receipt of Error Message, Set Status Bit
Message Format
Write Completion Indication
Read Completion Indication
Device-Specific Error Handling
Chapter 18: 64-Bit Transactions
General Format of Timing Diagram Descriptions
64-Bit Data Transfers and 64-Bit Addressing: Separate Capabilities
64-Bit Extension Signals
REQ64# and ACK64# Have Same Timing as FRAME# and DEVSEL#
In Attribute Phase, Upper Bus Reserved and Driven High
Block Length Remains the Same
Bursts Cannot Cross 264 Boundary
REQ64# Not Permitted in Dword Transactions
MSI Write Always Writes a Single 32-Bit Data Value
Bridge Must Support DAC on Both Interfaces
Width of Function's Connection to Bus
64-Bit Cards in 32-Bit Add-In Connectors
Pullups Prevent 64-Bit Extension From Floating When Not in Use
64-Bit Data Transfer Capability
Addressing Memory Above 4GB Boundary
Add-In Card Trace Length
Parity Generation and Checking
Chapter 19: Parity Generation and Checking
General Discussion of Parity Generation
General Discussion of Parity Checking
In Any Phase, Agent Driving AD Bus Supplies Parity
As in PCI, Even Parity Is Used
No Parity in Response Phase
Address Phase Parity
Attribute Phase Parity
Data Phase Parity
Part 3: Device Configuration
Chapter 20: Configuration Transactions
Configuration Software Mechanism Same as PCI
Configuration Transactions Can Only Flow Downstream
Special Cycle Request Can Flow Upstream or Downstream
Type 0: Access Registers in Function on This Bus
Type 1: Access Registers in Function on Bus Farther Out in Hierarchy
Type 0 Configuration Transactions
Type 1 Configuration Transactions
Arbiter's Treatment of Configuration Access
Generation of Special Cycle Under Software Control
Chapter 21: Non-Bridge Configuration Registers
Detecting a PCI-X Capable Bridge
Detecting Capabilities of Functions on Bus
Most PCI Configuration Registers Remain Unchanged
Some PCI Con fig Registers Affected by Protocol Mode
Function's PCI-X Capability Register Set
Chapter 22: Bridge Configuration Registers
Discovering a PCIX-to-PCIX Bridge
Many Bridge PCI Configuration Registers Unchanged
Some Bridge PCI Configuration Registers Affected by Mode
Bridge's PCLX Capability Register Set
Optional Bridge Registers
Part 4: Load Tuning
Chapter 23: Load Tuning Mechanisms
Introduction to Load Tuning
Non-Bridge Function Tuning
Bridge Tuning
Part 5: PCI-X Bridges
Chapter 24: PCIX-to-PCIX Bridges
Performs Same Function as a PCI-to-PCI Bridge
Support for DAC Command
Bus Width
Memory Writes Crossing Bridge Are Always Posted
Other Transactions Crossing Bridge Are Always Split
How the Bridge Claims Split Completions
When Bridge Can Use Retry or Disconnect At Next ADB
Interfaces Can Be in Different Modes/Speeds
Translating PCI to PCI-X
Translating PCI-X to PCI
Error Handling
Buffer Size
When a Request Is Bigger Than the Bridge Buffer
Application Bridge
Bridge Acceptance Rules
Ordering and Passing Rules
Decomposing Split Transactions (sounds morbid!)
Chapter 25: Locked Transaction Series
Definition of Downstream and Upstream
Basics
Only Host/PCIX Bridge Originates Downstream Locked Series
PCI-X Bridges Only Pass Locked Series Downstream
Only EISA Bridge Originates Upstream Locked Traffic
Application Bridge May or May Not Support Locking
EISA Bridge Supports LOCK# As Input, Not as Output
Non-Bridge Devices Ignore LOCK#
Sequence of Events
Split Completion Error Message Terminates Lock
Upstream Bridge (Initiating Bridge) Rules
Downstream Bridge (Target Bridge) Rules
Arbitration
Starting Locked Transaction Series
Continuing Locked Transaction Series
Attempted Access to Bridge by Device Other Than Owner
Last Transaction in Locked Series
When Bridge Starts Second Series Immediately After First
Retry Issued to Owner Not a Problem
DAC Command Lock Timing
Part 6: Error Detection and Handling
Chapter 26: Error Detection and Handling
Handling of a Target Abort
Handling of a Master Abort
Target Handling of Address or Attribute Phase Parity Error
Data Phase Parity
Split Read Errors
Requester Handling of Unexpected Split Completion
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