Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public
Document Table of Contents

2.3.4.1.7. External Memory

The EMAC is integrated with several external memory for different applications. The following technology specific memory modules are added and connected to the data bus, address, and control signals of the XGMAC core:

  • RX FIFO – 16 KB RAM to store RX DMA channel data 3
  • TX FIFO – 32 KB RAM to store TX DMA channel data3
  • TCP/IP Segmentation Offload (TSO) – 512 Bytes RAM to TCP/IP headers on the TX path 4
  • Descriptor Cache – 4 KB RAM to store the pre-fetched descriptors of all the DMAs active in the controller 5)
  • Gate Control List (GCL) – 2 KB RAM to store GCL on the TX path 6
3 All TX queues (8) share the TX FIFO memory and all RX queues (8) share the RX FIFO memory. The application can program the size of the FIFO memory allocated to each TX or RX queue.
4 The memory size each TSO channel (128 bytes) gets multiplied by the number of DMA channels (4) requiring the TSO feature.
5 For 128 descriptors per DMA channel.
6 For GCL depth of 256, the requirement is to double the size (512) to accommodate a shadow memory used for GCL operations.