QDMA Subsystem - 3.3 English

Versal ACAP CPM DMA and Bridge Mode for PCI Express Product Guide (PG347)

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3.3 English

QDMA mode enables the use of PCIE Controller 0 QDMA or PCIE Controller 1 QDMA. QDMA mode provides two connectivity variants: AXI Streaming, and AXI Memory Mapped. Both variants can be enabled simultaneously.

AXI Streaming
QDMA Streaming mode can be used in applications where the nature of the data traffic is streaming with source and destination IDs instead of a specific memory address location, such as network accelerators, network quality of service managers, or firewalls.
AXI Memory Mapped
QDMA Memory Mapped mode can be used in applications where the nature of the data traffic is addressable memory, such as moving data between a host and a card, such as an acceleration platform.

The main difference between XDMA mode and QDMA mode is that while XDMA mode supports up to 4 independent data streams, QDMA mode can support up to 2048 independent data streams. Based on this strength, QDMA mode is typically used for applications that require many queues or data streams that need to be virtually independent from each other. QDMA mode is the only DMA mode that can support multiple functions, either physical functions or single root I/O virtualization (SR-IOV) virtual functions.

QDMA mode can be used in conjunction with AXI Bridge mode. For more details on AXI Bridge mode, which is described in the next section.