[RTEMS Project] #5000: Implement POSIX Asynchronous IO

[RTEMS trac]

#5000: Implement POSIX Asynchronous IO
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  Reporter:  Joel Sherrill  |      Owner:  (none)
      Type:  enhancement    |     Status:  new
  Priority:  normal         |  Milestone:
 Component:  posix          |    Version:
  Severity:  normal         |   Keywords:  SoC, POSIX
Blocked By:                 |   Blocking:
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 RTEMS does not currently support POSIX Asynchronous IO as defined by The
 Open Group. These methods and associated constants are prototyped by the
 [​http://www.opengroup.org/onlinepubs/009695399/basedefs/aio.h.html
 <aio.h>] header file which is cpukit/posix/include/aio.h in the RTEMS
 source tree. The following methods have already been implemented but
 should be reviewed against the POSIX specification to ensure they are as
 complete as possible:

 - ​aio_read()
 ​- aio_write()
 ​- aio_cancel()
 ​- aio_error()
 ​- aio_return()

 The implementation of the above AIO methods includes a server thread which
 performs the user's AIO requests. These AIO methods request a SINGLE
 operation.

 The method ​lio_listio() is not implemented currently in RTEMS. The
 current implementation between the aio_ methods and the server thread will
 need to grow to support a list. The straightforward way to accomplish this
 is to modify the current aio_ infrastructure to treat a single aio_
 request as a list of one. Then the lio_listio() should be a simple
 modification.

 The current implementation leans to a long-ish function to process AIO
 requests. This processing should be refactored so while iterating the
 list, the server thread calls a helper method for each request type.

 The implementation has a single server thread. The server thread
 characteristics such as stack size and priority should be application
 configurable.

 There will need to be tests added for the new functionality. Coverage will
 need to be reviewed for the AIO functionality.

 Possible Mentors: Joel Sherrill, Gedare Bloom, Chris Johns, Kinsey Moore

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Ticket URL: <http://devel.rtems.org/ticket/5000>
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