source: rtems-docs/develenv/directory.rst @ 489740f

.. comment SPDX-License-Identifier: CC-BY-SA-4.0

Directory Structure
###################

The RTEMS directory structure is designed to meet
the following requirements:

- encourage development of modular components.

- isolate processor and target dependent code, while
  allowing as much common source code as possible to be shared
  across multiple processors and target boards.

- allow multiple RTEMS users to perform simultaneous
  compilation of RTEMS and its support facilities for different
  processors and targets.

The resulting directory structure has processor and
board dependent source files isolated from generic files.  When
RTEMS is configured and built, object directories and
an install point will be automatically created based upon
the target CPU family and BSP selected.

The placement of object files based upon the selected BSP name
ensures that object files are not mixed across CPUs or targets.
This in combination with the makefiles allows the specific
compilation options to be tailored for a particular target
board.  For example, the efficiency of the memory subsystem for
a particular target board may be sensitive to the alignment of
data structures, while on another target board with the same
processor memory may be very limited.  For the first target, the
options could specify very strict alignment requirements, while
on the second the data structures could be *packed* to conserve
memory.  It is impossible to achieve this degree of flexibility
without providing source code.

The RTEMS source tree is organized based on the following variables:

- functionality,

- target processor family,

- target processor model,

- peripherals, and

- target board.

Each of the following sections will describe the
contents of the directories in the RTEMS source
tree.  The top of the tree will be referenced
as ``${RTEMS_ROOT}`` in this discussion.

.. COMMENT: Top Level Tree

.. COMMENT: @ifset use-ascii
.. code:: c

    rtems-VERSION
    |
    +--------+----+----+----+--+-----+---+-------+--------+
    |        |    |    |       |     |   |       |        |
    aclocal automake c contrib  cpukit doc make testsuites tools

.. COMMENT: @end ifset

``${RTEMS_ROOT}/aclocal/``
    This directory contains the custom M4 macros which are available to
    the various GNU autoconf ``configure.ac`` scripts throughout
    the RTEMS source tree.  GNU autoconf interprets ``configure.ac``
    files to produce the ``configure`` files used to tailor
    RTEMS build for a particular host and target environment.  The
    contents of this directory will not be discussed further in this
    document.

``${RTEMS_ROOT}/automake/``
    This directory contains the custom GNU automake fragments
    which are used to support the various ``Makefile.am``
    files throughout the RTEMS source tree.  The
    contents of this directory will not be discussed
    further in this document.

``${RTEMS_ROOT}/c/``
    This directory is the root of the portions of the RTEMS source
    tree which must be built tailored for a particular CPU model
    or BSP.  The contents of this directory will be discussed
    in the `c/ Directory`_ section.

``${RTEMS_ROOT}/contrib/``
    This directory contains contributed support software.  Currently
    this directory contains the RPM specifications for cross-compilers
    hosted on GNU/Linux that target various operating systems
    including MinGW, Cygwin, FreeBSD, and Solaris.  The
    cross-compilers produced using these specifications are then
    used in a Canadian cross build procedure to produce the various
    RTEMS toolsets on a GNU/Linux host.
    This directory also contains RPM specifications for the
    prebuilt cross-compilation toolsets provided by the
    RTEMS project.  There are separate subdirectories
    for each of the components in the RTEMS Cross Compilation
    Environment unde the  ``contrib/crossrpms/`` directory.
    This directory is configured, built, and installed separately
    from the RTEMS executive and tests.  This directory will not
    be discussed further in this document.

``${RTEMS_ROOT}/cpukit/``
    This directory is the root for all of the "multilib'able"
    portions of RTEMS.  This is a GNU way of saying the
    contents of this directory can be compiled like the
    C Library (``libc.a``) and the functionality is
    neither CPU model nor BSP specific.  The source code
    for most RTEMS services reside under this directory.
    The contents of this directory will be discussed
    in the `CPU Kit Directory`_ section.

``${RTEMS_ROOT}/doc/``
    This directory is the root for all RTEMS documentation.
    The source for RTEMS is written in GNU TeXinfo and
    used to produce HTML, PDF, and "info" files.
    The RTEMS documentation is configured, built,
    and installed separately from the RTEMS executive and tests.
    The contents of this directory will be discussed
    in the `Documentation Directory`_ section.

``${RTEMS_ROOT}/make/``
    This directory contains files which support the
    RTEMS Makefile's.  From a user's perspective, the
    most important parts are found in the ``custom/``
    subdirectory.  Each ".cfg" file in this directory
    is associated with a specific BSP and describes
    the CPU model, compiler flags, and procedure to
    produce an executable for the target board.
    These files are described in detail in the*RTEMS BSP and Device Driver Development Guide*
    and will not be discussed further in this document.

``${RTEMS_ROOT}/testsuites/``
    This directory contains the test suites for the
    various RTEMS APIs and support libraries.  The
    contents of this directory are discussed in the `testsuites/ Test Suites`_ section.

``${RTEMS_ROOT}/tools/``
    This directory contains RTEMS specific support utilities which
    execute on the development host.  These utilities are divided
    into subdirectories based upon whether they are used in the process
    of building RTEMS and applications, are CPU specific, or are
    used to assist in updating the RTEMS source tree and applications.
    The support utilities used in the process of building RTEMS are
    described in `RTEMS Specific Utilities`_.  These are the
    only components of this subtree that will be discussed in this
    document.

.. COMMENT: c/ Directions

c/ Directory
============

The ``${RTEMS_ROOT}/c/`` directory was formerly
the root directory of all RTEMS source code.  At this time, it contains
the root directory for only those RTEMS components
which must be compiled or linked in a way that is specific to a
particular CPU model or board.  This directory contains the
following subdirectories:

``${RTEMS_ROOT}/c/src/``
    This directory is logically the root for the RTEMS components
    which are CPU model or board dependent.  Thus this directory
    is the root for the BSPs and the Ada Test Suites as well
    as CPU model and BSP dependent libraries.  The contents of
    this directory are discussed in the `c/src/ Directory`_ section.

.. COMMENT: c/src/ Directory

c/src/ Directory
----------------

As mentioned previously, this directory is logically
the root for the RTEMS components
which are CPU model or board dependent.  The
following is a list of the subdirectories in this
directory and a description of each.

``${RTEMS_ROOT}/c/src/aclocal/``
    This directory contains the custom M4 macros which are available to
    the various GNU autoconf ``configure.ac`` scripts throughout
    this portion of the RTEMS source tree.  GNU autoconf interprets``configure.ac`` files to produce the ``configure`` files used
    to tailor RTEMS build for a particular host and target environment.  The
    contents of this directory will not be discussed further in this
    document.

``${RTEMS_ROOT}/c/src/ada/``
    This directory contains the Ada95 language bindings to the
    RTEMS Classic API.

``${RTEMS_ROOT}/c/src/ada-tests/``
    This directory contains the test suite for the Ada
    language bindings to the Classic API.

``${RTEMS_ROOT}/c/src/automake/``
    This directory contains files which are "Makefile fragments."
    They are included as required by the various ``Makefile.am``
    files throughout this portion of the RTEMS source tree.

``${RTEMS_ROOT}/c/src/lib/``
    This directory contains the directories ``libbsp/``
    and ``libcpu/`` which contain the source code for
    the Board Support Packages (BSPs) and CPU Model
    specific source code for RTEMS.
    The ``libbsp/`` is organized based upon the CPU
    family and boards BSPs.  The contents of ``libbsp/``
    are discussed briefly in `c/src/lib/libbsp BSP Directory`_
    and presented in detail in the*RTEMS BSP and Device Driver Development Guide*.
    The ``libcpu/`` directory is also organized by
    CPU family with further divisions based upon CPU
    model and features that are shared across CPU models
    such as caching and DMA.

``${RTEMS_ROOT}/c/src/libchip/``
    This directory contains device drivers for various
    peripheral chips which are designed to be CPU and
    board dependent.  This directory contains a variety
    of drivers for serial devices, network interface
    controllers, shared memory and real-time clocks.

``${RTEMS_ROOT}/c/src/librtems++/``
    This directory contains C++ classes which map to the RTEMS
    Classic API.

``${RTEMS_ROOT}/c/src/make/``
    This directory is used to generate the bulk of the supporting
    rules files which are installed as part of the Application Makefiles.
    This file contains settings for various Makefile variables to
    tailor them to the particular CPU model and BSP configured.

``${RTEMS_ROOT}/c/src/nfsclient/``
    This directory contains a Network File System (NFS) client
    for RTEMS.  With this file system, a user's application can
    access files on a remote computer.

``${RTEMS_ROOT}/c/src/optman/``
    This directory contains stubs for the RTEMS Classic API
    Managers which are considered optional and whose use
    may be explicitly forbidden by an application.  All of the
    directive implementations in this Optional Managers
    return ``E_NOTCONFIGURED``.

``${RTEMS_ROOT}/c/src/support/``
    This directory exists solely to generate the RTEMS
    version string which includes the RTEMS version,
    CPU architecture, CPU model, and BSP name.

``${RTEMS_ROOT}/c/src/wrapup/``
    This directory is responsible for taking the individual
    libraries and objects built in each of the components
    in the RTEMS source tree and bundling them together to form
    the single RTEMS library ``librtemsbsp.a``.  This
    library contains all BSP and CPU model specific software.

.. COMMENT: c/src/lib/libbsp BSP Directory

c/src/lib/libbsp BSP Directory
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The "libbsp" directory contains a directory for each CPU family supported
by RTEMS.  Beneath each CPU directory is a directory for each BSP for that
processor family.

.. COMMENT: Tree 7 - C BSP Library

The "libbsp" directory provides all the BSPs provided with this
release of the RTEMS executive.  The subdirectories are
divided,  as discussed previously, based on specific processor
family, then further broken down into specific target board
environments.  The "no_cpu" subdirectory provides a starting point
template BSP which can be used to develop a specific BSP for an
unsupported target board.  The files in this subdirectory may aid
in preliminary testing of the RTEMS development environment that has
been built for no particular target in mind.

Below each CPU dependent directory is a directory for each target BSP
supported in this release.

Each BSP provides the modules which comprise an RTEMS BSP.  The
modules are separated into the subdirectories "clock", "console",
"include", "shmsupp", "startup", and "timer" as shown in the following
figure:

.. COMMENT: Tree 8 - Each BSP

.. COMMENT: @ifset use-ascii
.. code:: c

    Each BSP
    |
    +-----------+----------+-----+-----+----------+----------+
    |           |          |           |          |          |
    clock      console    include     shmsupp    startup     timer

.. COMMENT: @end ifset

.. COMMENT: CPU Kit Directory

CPU Kit Directory
=================

.. COMMENT: The @code{cpukit/} directory structure is as follows:

.. COMMENT: CPU Kit Tree

.. COMMENT: @ifset use-ascii

.. COMMENT: @example

.. COMMENT: @group

.. COMMENT: cpukit

.. COMMENT: |

.. COMMENT: +-+-+-+-+

.. COMMENT: |           |          |           |          |

.. COMMENT: posix       rtems       sapi       score     wrapup

.. COMMENT: @end group

.. COMMENT: @end example

.. COMMENT: @end ifset

The ``cpukit/`` directory contains a set of subdirectories which
contains the source files comprising the executive portion of
the RTEMS development environment as well as portable support
libraries such as support for the C Library and filesystems.
The API specific and "SuperCore" (e.g. ``score/`` directory)
source code files are separated into distinct directory trees.

The following is a description of each of the subdirectories
under ``cpukit/``:

``${RTEMS_ROOT}/cpukit/aclocal/``
    This directory contains the custom M4 macros which are available to
    the various GNU autoconf ``configure.ac`` scripts throughout
    the CPU Kit portion of the RTEMS source tree.
    GNU autoconf interprets ``configure.ac``
    files to produce the ``configure`` files used to tailor
    RTEMS build for a particular host and target environment.  The
    contents of this directory will not be discussed further in this
    document.

``${RTEMS_ROOT}/cpukit/automake/``
    This directory contains files which are "Makefile fragments."
    They are included as required by the various ``Makefile.am``
    files throughout the CPU Kit portion of the RTEMS source tree.

``${RTEMS_ROOT}/cpukit/ftpd/``
    This directory contains the RTEMS ftpd server.

``${RTEMS_ROOT}/cpukit/httpd/``
    This directory contains the port of the GoAhead
    web server to RTEMS.

``${RTEMS_ROOT}/cpukit/include/``
    This directory contains header files which are private to
    RTEMS and not considered to be owned by any other component
    in the CPU Kit.

``${RTEMS_ROOT}/cpukit/libblock/``
    This directory contains support code for using
    Block Devices such as hard drives, floppies, and
    CD-ROMs.  It includes the generic IO primitives
    for block device drivers, disk caching support,
    and a RAM disk block device driver.

``${RTEMS_ROOT}/cpukit/libcsupport/``
    This directory contains the RTEMS specific support routines
    for the Newlib C Library.  This includes what are referred
    to as system calls and found in section 2 of the traditional
    UNIX manual.   In addition, it contains a thread-safe
    implementation of the Malloc family of routines as well
    as BSD and POSIX services not found in Newlib.

``${RTEMS_ROOT}/cpukit/libfs/``
    This directory contains the various non-networked
    filesystem implementations for RTEMS.  It includes
    the In-Memory FileSystem (IMFS), the mini-IMFS,
    and FAT filesystems.

``${RTEMS_ROOT}/cpukit/libi2c/``
    This directory contains the RTEMS I2C framework.

``${RTEMS_ROOT}/cpukit/libmd/``
    This directory contains a port of the standard MD5
    checksum code.

``${RTEMS_ROOT}/c/src/libmisc/``
    This directory contains support facilities which
    are RTEMS specific but otherwise unclassified.  In
    general, they do not adhere to a standard API.
    Among the support facilities in this directory are
    a ``/dev/null`` device driver, the Stack
    Overflow Checker, a mini-shell, the CPU and
    rate monotonic period usage monitoring libraries,
    and a utility to "dump a buffer" in a nicely
    formatted way similar to many ROM monitors.

``${RTEMS_ROOT}/cpukit/libnetworking/``
    This directory contains the port of the FreeBSD
    TCP/IP stack to RTEMS.

``${RTEMS_ROOT}/cpukit/librpc/``
    This directory contains the port of the FreeBSD
    RPC/XDR source to RTEMS.

``${RTEMS_ROOT}/cpukit/libpci/``
    This directory contains RTEMS PCI Library.

``${RTEMS_ROOT}/cpukit/posix/``
    This directory contains the RTEMS implementation
    of the threading portions of the POSIX API.

``${RTEMS_ROOT}/cpukit/pppd/``
    This directory contains a port of the free implementation
    of the PPPD network protocol.

``${RTEMS_ROOT}/cpukit/rtems/``
    This directory contains the implementation of the
    Classic API.

``${RTEMS_ROOT}/cpukit/sapi/``
    This directory contains the implementation of RTEMS
    services which are required but beyond the realm
    of any standardization efforts.  It includes
    initialization, shutdown, and IO services.

``${RTEMS_ROOT}/cpukit/score/``
    This directory contains the "SuperCore" of RTEMS.
    All APIs are implemented in terms of SuperCore services.
    For example, Classic API tasks and POSIX threads
    are all implemented in terms of SuperCore threads.
    This provides a common infrastructure and a high degree
    of interoperability between the APIs.  For example,
    services from all APIs may be used by any task/thread
    independent of the API used to create it.
    Within the ``score/`` directory the CPU dependent modules are found.
    The ``score/cpu/`` subdirectory contains a subdirectory for each
    target CPU supported by this release of the RTEMS
    executive.  Each processor directory contains the CPU dependent
    code necessary to host RTEMS.  The ``no_cpu`` directory provides a
    starting point for developing a new port to an unsupported
    processor.  The files contained within the ``no_cpu`` directory
    may also be used as a reference for the other ports to specific
    processors.

``${RTEMS_ROOT}/cpukit/shttpd/``
    This directory contains the port of the Simple HTTPD
    web server to RTEMS.

``${RTEMS_ROOT}/cpukit/telnetd/``
    This directory contains the RTEMS telnetd server.

``${RTEMS_ROOT}/cpukit/wrapup/``
    This directory is responsible for taking the individual
    libraries and objects built in each of the components
    in the RTEMS CPU Kit source tree and bundling them
    together to form the single RTEMS library ``librtemscpu.a``.  This
    library contains all BSP and CPU model specific software.

``${RTEMS_ROOT}/cpukit/zlib/``
    This directory contains a port of the GNU Zlib compression
    library to RTEMS.

.. COMMENT: testsuites/ Test Suites

testsuites/ Test Suites
=======================

This directory provides all of the RTEMS Test Suite
except those for the Classic API Ada95 binding
This includes the single processor tests, multiprocessor tests,
timing tests, library tests, and sample tests.   Additionally,
subdirectories for support functions and test related header
files are provided.  The following table lists the test suites
currently included with the RTEMS and the directory in which
they may be located:

``${RTEMS_ROOT}/testsuites/libtests/``
    This directory contains the test suite for the
    various RTEMS support components.

``${RTEMS_ROOT}/testsuites/mptests/``
    This directory contains the test suite for the
    multiprocessor support in the Classic API.
    The tests provided address two node configurations
    and provide coverage for the multiprocessor code found
    in RTEMS.

``${RTEMS_ROOT}/testsuites/psxtests/``
    This directory contains the test suite for the
    RTEMS POSIX API.

``${RTEMS_ROOT}/testsuites/samples/``
    This directory provides sample application tests
    which aid in the testing a newly built RTEMS environment, a new
    BSP, or as starting points for the development of an application
    using the RTEMS executive.  They are discussed in `Sample Applications`_.

``${RTEMS_ROOT}/testsuites/sptests/``
    This directory contains the test suite for the RTEMS
    Classic API when executing on a single processor.
    The tests were originally designed to provide
    near complete test coverage for the entire
    executive code.  With the addition of multiple APIs,
    this is no longer the case as some SuperCore functionality
    is not available through the Classic API.  Thus
    some functionality in the SuperCore is only covered
    by tests in the POSIX API Test Suites.

``${RTEMS_ROOT}/testsuites/support/``
    This directory contains support software and header files
    for the various test suites.

``${RTEMS_ROOT}/testsuites/tmtests/``
    This directory contains the timing test suite for
    the RTEMS Classic API.  This include tests that
    benchmark each directive in the Classic API
    as well as a set of critical SuperCore functions.
    These tests are important for helping to verify
    that RTEMS performs as expected on your target hardware.
    It is not uncommon to discover mistakes in board
    initialization such as caching being disabled as
    a side-effect of analyzing the results of these tests.

``${RTEMS_ROOT}/testsuites/tools/``
    This directory contains tools which execute on
    the development host and aid in executing and
    evaluating the results of the test suite.  The
    tools ``difftest`` compares the output of one
    or more tests with the expected output.  If you
    place the output of all the ``tmtests/`` in
    a single file, then the utility ``sorttimes``
    will be able to produce a report organizing the
    execution times by manager.

.. COMMENT: Documentation Directory

Documentation Directory
=======================

This directory contains the source code for all RTEMS documentation
in ``TexInfo`` format as well as utilities used in the generation
of the RTEMS documentation set.  This source code is used to produce
the RTEMS documentation in various formats including PDF, HTML,
and PostScript.

``${RTEMS_ROOT}/doc/ada_user/``
    This directory contains the source code for the *RTEMS
    Applications Ada User's Guide* which documents the Ada95
    binding to the Classic API.  This manual is produced from
    from the same source base as the *RTEMS Application
    C User's Guide*.

``${RTEMS_ROOT}/doc/bsp_howto/``
    This directory contains the source code for the*RTEMS BSP and Device Driver Development Guide*.

``${RTEMS_ROOT}/doc/common/``
    This directory contains the source code for the files which
    are shared across multiple manuals in the RTEMS Documentation Set.
    This includes the copyright page as well as the timing
    tables which can be filled in on a per BSP basis in the
    CPU supplements.

``${RTEMS_ROOT}/doc/cpu_supplement/``
    This directory contains the source code for the
    RTEMS CPU Supplement.

``${RTEMS_ROOT}/doc/develenv/``
    This directory contains the source code for the*RTEMS Development Environment Guide*.  This is
    the document you are currently reading.

``${RTEMS_ROOT}/doc/filesystem/``
    This directory contains the source code for the*RTEMS Filesystem Design Guide*.  This manual
    is a continuous work in process as it attempts to
    capture the design of the interface between system
    calls and filesystem implementations as well as the
    information required by those implementing filesystems.

``${RTEMS_ROOT}/doc/images/``
    This directory contains the source code for the graphics
    used in the HTML version of the RTEMS Documentation.

``${RTEMS_ROOT}/doc/networking/``
    This directory contains the source code for the*RTEMS Network Supplement*.

``${RTEMS_ROOT}/doc/new_chapters/``
    This directory contains the source code for the new documentation
    components which have not yet been collected into a new manual or
    merged into an existing document.  Currently, this primarily
    contains draft documentation for some portions of
    the facilities implemented in ``${RTEMS_ROOT}/c/src/libmisc/``.

``${RTEMS_ROOT}/doc/porting/``
    This directory contains the source code for the*RTEMS Porting Guide*.

``${RTEMS_ROOT}/doc/posix1003.1/``
    This directory contains the source code for the*RTEMS POSIX 1003.1 Compliance Guide*.

``${RTEMS_ROOT}/doc/posix_users/``
    This directory contains the source code for the*RTEMS POSIX API User's Guide*.  It is important to
    note that RTEMS' support for POSIX is a combination of
    functionality provided by RTEMS and the Newlib C Library
    so some functionality is documented by Newlib.

``${RTEMS_ROOT}/doc/relnotes/``
    This directory contains the source code for a formally
    release notes document.  This has not been used for
    recent RTEMS releases.

``${RTEMS_ROOT}/doc/started/``
    This directory contains the source code for the*Getting Started with RTEMS for C/C++ Users* manual.

``${RTEMS_ROOT}/doc/tools/``
    This directory contains the source code for the tools
    used on the development host to assist in producing the
    RTEMS Documentation.  The most important of these tools
    is ``bmenu`` which generates the hierarchical node
    linking commands based upon chapter, section, and
    subsection organization.

``${RTEMS_ROOT}/doc/user/``
    This directory contains the source code for the *RTEMS
    Applications C User's Guide* which documents the Classic API.

.. COMMENT: COPYRIGHT (c) 1989-2007.

.. COMMENT: On-Line Applications Research Corporation (OAR).

.. COMMENT: All rights reserved.