R-tile Avalon® Streaming Intel® FPGA IP for PCI Express* User Guide

ID 683501
Date 12/13/2021
Public

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3.2.1.2. Implementation

The VF configuration space is implemented in R-tile logic, and does not require FPGA fabric resources.

Accessing VF PCIe Information:

Due to the limited number of pins between R-tile and the FPGA fabric, the PCIe configuration space for VFs is not directly available to the user application.

User application can use the following methods to retrieve necessary information (bus master enable, MSI-X etc…):

Accessing VF PCIe Information:

VF IDs are calculated within R-tile. User application has sideband signals pX_rx_st_vfnum_o[10:0] and pX_rx_st_vfactive_o with the TLP to identify the associated VFs within the PFs.

BDF Assignments:

When SR-IOV is enabled, the ARI capability is always enabled.

The R-tile IP for PCIe automatically calculates the completer/requester ID on the Transmit side.

User application needs to provide the VF and PF information in the Header as shown below:

(For X16, sn is either s0 or s1. For X8, sn is s0).

  • pX_tx_st_hdr_sn_i[127]: must be set to 0
  • pX_tx_st_hdr_sn_i[83]: pX_tx_st_vfactive_i
  • pX_tx_st_hdr_sn_i[82:80]: pX_tx_st_pfnum_i[2:0]
  • pX_tx_st_hdr_sn_i[95:84]: pX_tx_st_vfnum_i[10:0]

In the following example, VF3 of PF1 is receiving and sending a request:

For the Receive TLP:

pX_rx_st_pfnum_o = 1h indicating that a VF associated with PF1 is making the request.

pX_rx_st_vfnum_o = 3h, and pX_rx_st_vfactive_o = 1 indicating that VF3 of PF1 is the active VF.

For the Transmit TLP of VF3 associated with PF1:
  • pX_tx_st_hdr_sn_i[83] = 1h
  • pX_tx_st_hdr_sn_i[82:80] = 1h
  • pX_tx_st_hdr_sn_i[95:84] = 3h

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