IO_SETUP(2)		   Linux Programmer's Manual		   IO_SETUP(2)



NAME
       io_setup - create an asynchronous I/O context

SYNOPSIS
       #include <linux/aio_abi.h>	   /* Defines needed types */

       int io_setup(unsigned nr_events, aio_context_t *ctx_idp);

       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION
       The io_setup() system call creates an asynchronous I/O context suitable
       for concurrently processing nr_events operations.  The ctx_idp argument
       must  not point to an AIO context that already exists, and must be ini-
       tialized to 0 prior to the call.	 On successful	creation  of  the  AIO
       context, *ctx_idp is filled in with the resulting handle.

RETURN VALUE
       On success, io_setup() returns 0.  For the failure return, see NOTES.

ERRORS
       EAGAIN The  specified  nr_events	 exceeds the user's limit of available
	      events, as defined in /proc/sys/fs/aio-max-nr.

       EFAULT An invalid pointer is passed for ctx_idp.

       EINVAL ctx_idp is not initialized, or the specified  nr_events  exceeds
	      internal limits.	nr_events should be greater than 0.

       ENOMEM Insufficient kernel resources are available.

       ENOSYS io_setup() is not implemented on this architecture.

VERSIONS
       The asynchronous I/O system calls first appeared in Linux 2.5.

CONFORMING TO
       io_setup()  is  Linux-specific  and should not be used in programs that
       are intended to be portable.

NOTES
       Glibc does not provide a wrapper function for this  system  call.   You
       could  invoke  it  using syscall(2).  But instead, you probably want to
       use the io_setup() wrapper function provided by libaio.

       Note that the libaio wrapper function uses a  different	type  (io_con-
       text_t *)  for the ctx_idp argument.  Note also that the libaio wrapper
       does not follow the usual C library conventions for indicating  errors:
       on  error it returns a negated error number (the negative of one of the
       values  listed  in  ERRORS).   If  the  system  call  is	 invoked   via
       syscall(2),  then  the  return  value follows the usual conventions for
       indicating an error: -1, with errno set	to  a  (positive)  value  that
       indicates the error.

SEE ALSO
       io_cancel(2), io_destroy(2), io_getevents(2), io_submit(2), aio(7)

COLOPHON
       This  page  is  part of release 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at
       https://www.kernel.org/doc/man-pages/.



Linux				  2013-06-21			   IO_SETUP(2)