io_uring mechanism where the application sets up an additional circular buffer (a buffer ring) of preallocated read buffers and registers it with the kernel. Each CQE tells the application which buffer the kernel chose and how much data it read. Recent kernels support incremental consumption: if only 3 bytes of a 16 KB buffer are read, the kernel resumes at the offset on the next read. Crucially, the same set of buffers can serve many concurrent read/receive operations, eliminating per-operation buffer allocation. Required for multi-shot read and receive operations.