DMA write error completion signal

[chen0228]

Hello, after writing 1500 bytes of data using m_axis_dma_write_desc_dma_addr, s_axis_dma_write_desc_status_valid is returned, and there is a chance that old data will appear in the PC memory. This means that it is not actually fully written. What is the reason? The memory is managed by DPDK. Looking forward to your reply

[alexforencich]

Gonna need a lot more information. It should be the case that the status is not returned until the write is on its way out the door on the PCIe link, in which case the situation you describe should be impossible as software would be informed by some other PCIe operation (register read, completion write, etc.) which would occur strictly after all of the write requests associated with the DMA operation, and PCIe ordering requirements guarantee that the results are consistent. However, it is possible that you're running in to some sort of caching issue, where software is not actually seeing what's in DRAM but instead a stale copy in the CPU cache.