Descriptor Metadata - 3.4 English

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

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3.4 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 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.