Multi Channel DMA Intel® FPGA IP for PCI Express User Guide

ID 683821
Date 1/14/2022
Public

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8.2.4. Request Structures

To request a DMA operation, the application uses rte_mbuf structure which contains packet information such as Physical address of segment buffer, length of the data in this descriptor, Number of segments, 8-byte userdata which is used to notify SOF and EOF of data.

Note: For the Avalon-ST Design, the application should pass the sof, eof and metadata to driver in the private structure added in rte_mbuf structure. sof and eof flags should be updated based on file size. For example, if file_size = 127, 0th descriptor should contains SOF flag should be set and 126th descriptor should contains EOF file should be set.

Metadata is private information and can be used for any purpose.

Structure of Private Data

struct private_data {
          uint64_t flags; /* SOF, EOF */
          uint64_t metadata; /* Private meta data */
};

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