Functional Description - 1.1 English

The main functions of the RAMA IP are as follows:

• Receive AXI4 Read/Write transactions on the AXI4 interface.
• Resize AXI transactions to a consistent burst size (burst fragment) of 64 or 128 bytes to and from the HBM subsystem. Bursts are resized for the following reasons:
  • The maximum permissible burst size for the HBM Subsystem is 512 bytes.
  • Reordering transactions is more efficient (buffer sizing) with smaller transactions.
  • Resizing bursts allows for transactions to be spread across memories, limiting congestion at a particular memory.
    Note: Fragmentation will always occur (that is, the maximum transaction size seen at the HBM subsystem will be the same as the "burst fragment size").
• Interleave burst fragments across HBM memories to prevent short-term congestion on a particular memory. This is an optional feature.
• ID substitution is applied to AXI AWID/ARID fields for each burst fragment.
  • For read transactions: Implement read ID substitution to supply different read IDs on different transactions. This prevents bandwidth limitations as discussed in the Overview section. Reorder returning read data to obey AXI transaction rules.
  • For write transactions: Implement write ID substitution to supply different write IDs on different transactions. This prevents bandwidth limitations as discussed in the Overview section. Reorder write responses to obey AXI transaction rules.
• Generate read/write AXI3 burst fragment transactions to/from HBM subsystem through the AXI3 Master interface.