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io_uring_prep_read_fixed(3) — Linux manual page

io_uring_prep_read_fixed(3)  liburing Manualio_uring_prep_read_fixed(3)

NAME        top

       io_uring_prep_read_fixed - prepare I/O read request with       registered buffer

SYNOPSIS        top

#include <liburing.h>void io_uring_prep_read_fixed(struct io_uring_sqe *sqe,intfd,void *buf,unsignednbytes,__u64offset,intbuf_index);

DESCRIPTION        top

       Theio_uring_prep_read_fixed(3) prepares an IO read request with a       previously registered IO buffer. The submission queue entrysqe is       setup to use the file descriptorfd to start readingnbytes into       the bufferbuf at the specifiedoffset, and with the buffer       matching the registered index ofbuf_index.       This works just likeio_uring_prep_read(3) except it requires the       use of buffers that have been registered withio_uring_register_buffers(3).  Thebuf andnbytes arguments must       fall within a region specified bybuf_index in the previously       registered buffer. The buffer need not be aligned with the start       of the registered buffer.       After the read has been prepared it can be submitted with one of       the submit functions.

RETURN VALUE        top

       None

ERRORS        top

       The CQEres field will contain the result of the operation. See       the related man page for details on possible values. Note that       where synchronous system calls will return-1on failure and seterrno to the actual error value, io_uring never useserrno.       Instead it returns the negatederrno directly in the CQEres       field.

SEE ALSO        top

io_uring_prep_read(3),io_uring_register_buffers(3)

COLOPHON        top

       This page is part of theliburing (A library for io_uring)       project.  Information about the project can be found at        ⟨https://github.com/axboe/liburing⟩.  If you have a bug report for       this manual page, send it to io-uring@vger.kernel.org.  This page       was obtained from the project's upstream Git repository       ⟨https://github.com/axboe/liburing⟩ on 2025-08-11.  (At that time,       the date of the most recent commit that was found in the       repository was 2025-08-02.)  If you discover any rendering       problems in this HTML version of the page, or you believe there is       a better or more up-to-date source for the page, or you have       corrections or improvements to the information in this COLOPHON       (which isnot part of the original manual page), send a mail to       man-pages@man7.orgliburing-2.1                February 13, 2022io_uring_prep_read_fixed(3)

Pages that refer to this page:io_uring_clone_buffers(3), io_uring_clone_buffers_offset(3), io_uring_prep_read_fixed(3), io_uring_register_buffers(3), io_uring_register_buffers_sparse(3), io_uring_register_buffers_tags(3), io_uring_register_buffers_update_tag(3)

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