From ac90f249e15cd2a850daa9e36e15f81ce1ff6550 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 6 Sep 2019 10:26:21 -0600 Subject: io_uring: expose single mmap capability After commit 75b28affdd6a we can get by with just a single mmap to map both the sq and cq ring. However, userspace doesn't know that. Add a features variable to io_uring_params, and notify userspace that the kernel has this ability. This can then be used in liburing (or in applications directly) to avoid the second mmap. Signed-off-by: Jens Axboe --- include/uapi/linux/io_uring.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h index 1e1652f25cc1..96ee9d94b73e 100644 --- a/include/uapi/linux/io_uring.h +++ b/include/uapi/linux/io_uring.h @@ -128,11 +128,17 @@ struct io_uring_params { __u32 flags; __u32 sq_thread_cpu; __u32 sq_thread_idle; - __u32 resv[5]; + __u32 features; + __u32 resv[4]; struct io_sqring_offsets sq_off; struct io_cqring_offsets cq_off; }; +/* + * io_uring_params->features flags + */ +#define IORING_FEAT_SINGLE_MMAP (1U << 0) + /* * io_uring_register(2) opcodes and arguments */ -- cgit v1.2.3