IORING_OFF_MMAP_MASK
switch (offset & IORING_OFF_MMAP_MASK) {
id = (offset & ~IORING_OFF_MMAP_MASK) >> IORING_OFF_PBUF_SHIFT;
id = (offset & ~IORING_OFF_MMAP_MASK) >> IORING_OFF_ZCRX_SHIFT;