Arria V Avalon-ST Interface for PCIe Solutions: User Guide

ID 683660
Date 5/12/2017
Document Table of Contents

8.5. Multi-Function Support

The Arria V Hard IP for PCI Express supports up to eight functions for Endpoints. You set up the each function under the Port Functions heading in the parameter editor. You can configure Arria V devices to include both Native and Legacy Endpoints. Each function replicates the Configuration Space Registers, including logic for Tag Tracking and Error detection.

Because the Configuration Space is replicated for each function, some Configuration Space Register settings may conflict. Arbitration logic resolves differences when settings contain different values across multiple functions. The arbitration logic implements the rules for resolving conflicts as specified in the PCI Express Base Specification 2.1. Examples of settings that require arbitration include the following features:

  • Link Control settings
  • Error detection and logging for non-function-specific errors
  • Error message collapsing
  • Maximum payload size (All functions use the largest specified maximum payload setting.)

    Altera strongly recommends that your software configure the Maximum payload size (in the Device Control register) with the same value across all functions.

  • Interrupt message collapsing

You can access the Configuration Space Registers for the active function using the LMI interface. In Root Port mode, you can also access the Configuration Space Registers using a Configuration Type TLP. Refer to Type 0 Configuration Space Registers for more information about the Configuration Space Registers.