Descriptor Metadata - 4.0 English

QDMA Subsystem for PCI Express Product Guide (PG302)

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4.0 English

Similar to bypass mode, the internal mode also provides a mechanism to pass information directly from the software to the user logic. In addition to address and length, the H2C Stream descriptor also has a 32b metadata field. This field is not used by the QDMA Subsystem for PCIe for the DMA operation. Instead, it is passed on to the user logic on the H2C AXI4-Stream tuser on every beat of the packet. Passing metadata on the tuser is not supported for a queue in bypass mode and consequently there is no input to provide the metadata on the QDMA H2C Stream bypass-in interface.