Xilinx KCU105 User Manual page 67

Application Data Driver
The user space application opens the application driver interface and operates write/read
system calls. The application driver performs these steps for each direction of data transfer:
S2C Direction
1. Receives a WRITE system call from the user application along with the user buffer.
2. Pins the user buffer pages to protect them from swapping.
3. Converts the pages to physical addresses.
4. Stores all page address and buffer information in a local data structure for
post-processing usage.
5. Calls the relevant data transfer API of the XDMA driver for transfer of packets.
6. In the process of registration with the XDMA driver, a callback function is registered and
invoked after the XDMA driver receives the completion of the packet.
7. The completed packet is queued in the driver.
8. The application periodically polls for the completion of packet by reading the driver's
queues.
C2S Direction
1. Sends free buffers from the user space by issuing a READ system call.
2. Pins the user buffer pages to protect them from swapping.
3. Converts the pages to physical addresses.
4. Stores all page address and buffer information in a local data structure for
post-processing usage.
5. Calls the relevant data transfer API of the XDMA driver for transfer of packet.
6. In the process of registration with the XDMA driver, a callback function is registered and
invoked after the XDMA driver receives a packet.
7. The received packet is queued in the driver.
8. The application periodically polls for receipt of a packet by reading the driver's queues.
PCIe Streaming Data Plane TRD
UG920 (v2017.1) June 01, 2017
Chapter 5: Targeted Reference Design Details and Modifications
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