linux raw io_uring struct

io_uring.h

struct io_uring_sqe {
                __u8 opcode;                  // opcode field that describes the operation code, example: IORING_OP_READV
                __u8 flags;                   // flags contains modifier flags
                __u16 ioprio;                 // ioprio is the priority of this request, see ioprio_set(2)
                __s32 fd;                     // fd is the file descriptor associated with the request
                __u64 off;                    // off holds the offset at which the operation should take place
                __u64 addr;                   // addr contains the address at which the operation should perform IO, if the op-code describes an operation that transfers data. If the
                                              // operation is a vectored read/write of some sort, this will be a pointer 
                                              // to an struct iovec array, as used by preadv(2), for
                                              // example. For a non-vectored IO transfer,
                                              // addr must contain the address directly
                __u32 len;                    // This carries into len, which is either a byte count for a non-vectored IO 
                                              // transfer, or a number of vectors described by
                                              // addr for a vectored IO transfer
                union {
                        __kernel_rwf_t rw_flags;        // Next follows a union of flags that are specific to the op-code
                        __u32 fsync_flags;
                        __u16 poll_events;
                        __u32 sync_range_flags;
                        __u32 msg_flags;
                };
                __u64 user_data;                        // untouched by the kernel
                union {
                        __u16 buf_index;                // buf_index will be described in the advanced use cases section
                        __u64 __pad2[3];       // unused, for future and padding in 64
                };
        };

// passed to kernel
struct io_uring_params {
                        __u32 sq_entries;
                        __u32 cq_entries;
                        __u32 flags;
                        __u32 sq_thread_cpu;
                        __u32 sq_thread_idle;
                        __u32 resv[5];
                        struct io_sqring_offsets sq_off; // i dont really trust this: https://github.com/torvalds/linux/blob/34afb82a3c67f869267a26f593b6f8fc6bf35905/include/uapi/linux/io_uring.h#L462
                        struct io_cqring_offsets cq_off; // same: https://github.com/torvalds/linux/blob/34afb82a3c67f869267a26f593b6f8fc6bf35905/include/uapi/linux/io_uring.h#L481
                };

struct io_sqring_offsets {
	__u32 head;
	__u32 tail;
	__u32 ring_mask;
	__u32 ring_entries;
	__u32 flags;
	__u32 dropped;
	__u32 array;
	__u32 resv1;
	__u64 user_addr;
};

struct io_cqring_offsets {
	__u32 head;
	__u32 tail;
	__u32 ring_mask;
	__u32 ring_entries;
	__u32 overflow;
	__u32 cqes;
	__u32 flags;
	__u32 resv1;
	__u64 user_addr;
};