Visible to Intel only — GUID: mdo1591741390147
Ixiasoft
Visible to Intel only — GUID: mdo1591741390147
Ixiasoft
3.1.1. H2D Data Mover
The Host-to-Device Data Mover (H2DDM) module transfers data from the host memory to local memory through the PCIe Hard IP and the Avalon-MM Write Master/Avalon-ST Source interface.
There are two modes of usage for the H2DDM: queue descriptors fetching and H2D data payload transfer.
When used for descriptor fetching, the destination of the completion data is internal descriptor FIFOs where descriptors are stored before being dispatched to the H2DDM or D2HDM for actual data transfer.
- First MemRd to the MRRS address boundary
- Following with MemRd’s of full MRRS size
- Last MemRd of the remaining partial MRRS
- Schedule MSI-X for a completed queue, if enabled
- Schedule Writeback Consumed Head Pointer for a completed queue, if enabled
- Update Consume Head Pointer for software polling
MSI-X and Writeback are memory write to host via the D2HDM to avoid race condition due to out-of-order writes. Based on the updated status, software can proceed with releasing the transmit buffer and reuse the descriptor ring entries.