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From:   Florian Weimer <fweimer@redhat.com>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     linux-aio@kvack.org, linux-block@vger.kernel.org,
        linux-api@vger.kernel.org, hch@lst.de, jmoyer@redhat.com,
        avi@scylladb.com, jannh@google.com
Subject: Re: [PATCH 05/18] Add io_uring IO interface
References: <20190201152414.23296-1-axboe@kernel.dk>
        <20190201152414.23296-6-axboe@kernel.dk>
Date:   Fri, 01 Feb 2019 19:20:57 +0100
In-Reply-To: <20190201152414.23296-6-axboe@kernel.dk> (Jens Axboe's message of
        "Fri, 1 Feb 2019 08:24:01 -0700")
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* Jens Axboe:

> +/*
> + * Filled with the offset for mmap(2)
> + */
> +struct io_sqring_offsets {
> +	__u32 head;
> +	__u32 tail;
> +	__u32 ring_mask;
> +	__u32 ring_entries;
> +	__u32 flags;
> +	__u32 dropped;
> +	__u32 array;
> +	__u32 resv[3];
> +};
> +
> +struct io_cqring_offsets {
> +	__u32 head;
> +	__u32 tail;
> +	__u32 ring_mask;
> +	__u32 ring_entries;
> +	__u32 overflow;
> +	__u32 cqes;
> +	__u32 resv[4];
> +};
> +
> +/*
> + * io_uring_enter(2) flags
> + */
> +#define IORING_ENTER_GETEVENTS	(1U << 0)
> +
> +/*
> + * Passed in for io_uring_setup(2). Copied back with updated info on success
> + */
> +struct io_uring_params {
> +	__u32 sq_entries;
> +	__u32 cq_entries;
> +	__u32 flags;
> +	__u32 resv[7];
> +	struct io_sqring_offsets sq_off;
> +	struct io_cqring_offsets cq_off;
> +};

I still think it might be a good idea to have one reserved __u64 field
for alignment purposes.

Thanks,
Florian