GTS AXI Multichannel DMA IP for PCI Express User Guide

ID 847470
Date 5/06/2025
Public

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B.2. MSI-X Memory Space

The MSI-X Table and Pending Bit Array (PBA) memory are mapped to the second MB space of the register address space. The actual amount of memory depends on the GTS AXI MCDMA IP configuration.

MSI-X Table

Each entry (vector) is 16 bytes (4 DWORDs) and is divided into Message Address, Data, and Mask (Vector Control) fields as shown in the figure below. Though the actual required space is smaller, the MSI-X Table is mapped to a 512 KB of space.

Figure 39. MSI-X Table Structure

MSI-X PBA

The MSI-X PBA memory space is mapped to a 512 KB region. The actual amount of memory depends on the IP configuration. The Pending Bit Array contains the Pending bits, one per MSI-X Table entry, in an array of QWORDs (64 bits). The PBA format is shown below.

Figure 40. MSI-X PBA Structure

Each DMA Channel is allocated 4 MSI-X vectors:

  • 2’b00: H2D DMA Vector
  • 2’b01: H2D Event Interrupt
  • 2’b10: D2H DMA Vector
  • 2’b11: D2H Event Interrupt