Scalable Scatter-Gather DMA Intel® FPGA IP User Guide

ID 823097
Date 4/07/2025
Public
Document Table of Contents

7.2. MSI-X Memory Space

The MSI-X Table and PBA memory is mapped to the second MB space (22’h10_0000 - 22’h1F_FFFF) of the Register address space. Allocated memory space can support up to 2048 MSI-X interrupts for a function. Actual amount of memory depends on the SSGDMA IP.

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. To support 2048 interrupts, MSI-X Table requires 32 KB of space per function but it is mapped to a 512 KB of space.
Figure 22. MSI-X Table Structure

MSI-X PBA

MSI-X PBA (Pending Bit Array) memory space is mapped to a 512 KB region. Actual amount of memory depends on the IP configuration. The Pending Bit Array contains the Pending bits, one per MSI-X Table entry, in array of QWORDs (64 bits) with read-only access. The PBA format is shown below.
Figure 23. MSI-X PBA Structure