185 lines
7.6 KiB
ReStructuredText
185 lines
7.6 KiB
ReStructuredText
******************************
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Customizing NSH Initialization
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******************************
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**Ways to Customize NSH Initialization**. There are three ways to
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customize the NSH start-up behavior. Here they are presented in order of
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increasing difficulty:
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#. You can extend the initialization logic in
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``boards/arm/stm32/stm3240g-eval/src/stm32_appinit.c``. The logic
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there is called each time that NSH is started and is good place in
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particular for any device-related initialization.
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#. You replace the sample code at ``apps/examples/nsh/nsh_main.c`` with
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whatever start-up logic that you want. NSH is a library at
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``apps/nshlib``. ``apps.examples/nsh`` is just a tiny, example
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start-up function (``CONFIG_USER_ENTRYPOINT``\ ()) that that runs
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immediately and illustrates how to start NSH If you want something
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else to run immediately then you can write your write your own custom
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``CONFIG_USER_ENTRYPOINT``\ () function and then start other tasks
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from your custom ``CONFIG_USER_ENTRYPOINT``\ ().
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#. NSH also supports a start-up script that executed when NSH first
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runs. This mechanism has the advantage that the start-up script can
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contain any NSH commands and so can do a lot of work with very little
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coding. The disadvantage is that is is considerably more complex to
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create the start-up script. It is sufficiently complex that is
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deserves its own paragraph
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NuttShell Start up Scripts
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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First of all you should look at `NSH Start-Up Script <#startupscript>`__
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paragraph. Most everything you need to know can be found there. That
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information will be repeated and extended here for completeness.
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**NSH Start-Up Script**. NSH supports options to provide a start up
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script for NSH. The start-up script contains any command support by NSH
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(i.e., that you see when you enter 'nsh> help'). In general this
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capability is enabled with ``CONFIG_NSH_ROMFSETC=y``, but has several
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other related configuration options as described with the `NSH-specific
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configuration settings <#nshconfiguration>`__ paragraph. This capability
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also depends on:
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- ``CONFIG_DISABLE_MOUNTPOINT=n``. If mount point support is disabled,
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then you cannot mount *any* file systems.
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- ``CONFIG_FS_ROMFS`` enabled. This option enables ROMFS file system
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support.
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**Default Start-Up Behavior**. The implementation that is provided is
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intended to provide great flexibility for the use of Start-Up files.
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This paragraph will discuss the general behavior when all of the
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configuration options are set to the default values.
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In this default case, enabling ``CONFIG_NSH_ROMFSETC`` will cause NSH to
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behave as follows at NSH start-up time:
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- NSH will create a read-only RAM disk (a ROM disk), containing a tiny
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ROMFS file system containing the following::
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`--init.d/
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`-- rcS
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Where ``rcS`` is the NSH start-up script.
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- NSH will then mount the ROMFS file system at ``/etc``, resulting in::
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|--dev/
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| `-- ram0
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`--etc/
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`--init.d/
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`-- rcS
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- By default, the contents of ``rcS`` script are::
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# Create a RAMDISK and mount it at /tmp
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mkrd -m 1 -s 512 1024
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mkfatfs /dev/ram1
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mount -t vfat /dev/ram1 /tmp
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- NSH will execute the script at ``/etc/init.d/rcS`` at start-up
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(before the first NSH prompt). After execution of the script, the
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root FS will look like::
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|--dev/
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| |-- ram0
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| `-- ram1
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|--etc/
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| `--init.d/
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| `-- rcS
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`--tmp/
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**Example Configurations**. Here are some configurations that have
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``CONFIG_NSH_ROMFSETC=y`` in the NuttX configuration file. They might
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provide useful examples:
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- ``boards/arm/stm32/hymini-stm32v/nsh2``
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- ``boards/arm/dm320/ntosd-dm320/nsh``
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- ``boards/sim/sim/sim/nsh``
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- ``boards/sim/sim/sim/nsh2``
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- ``boards/sim/sim/sim/nx``
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- ``boards/sim/sim/sim/nx11``
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- ``boards/sim/sim/sim/touchscreen``
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In most of these cases, the configuration sets up the *default*
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``/etc/init.d/rcS`` script. The default script is here:
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``apps/nshlib/rcS.template``. (The funny values in the template like
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``XXXMKRDMINORXXX`` get replaced via ``sed`` at build time). This
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default configuration creates a ramdisk and mounts it at ``/tmp`` as
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discussed above.
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If that default behavior is not what you want, then you can provide your
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own custom ``rcS`` script by defining ``CONFIG_NSH_ARCHROMFS=y`` in the
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configuration file.
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**Modifying the ROMFS Image**. The contents of the ``/etc`` directory
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are retained in the file ``apps/nshlib/nsh_romfsimg.h`` OR, if
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``CONFIG_NSH_ARCHROMFS`` is defined,
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``include/arch/board/nsh_romfsimg.h``. In order to modify the start-up
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behavior, there are three things to study:
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#. **Configuration Options.** The additional ``CONFIG_NSH_ROMFSETC``
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configuration options discussed with the other `NSH-specific
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configuration settings <#nshconfiguration>`__.
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#. ``tools/mkromfsimg.sh`` **Script**. The script
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``tools/mkromfsimg.sh`` creates ``nsh_romfsimg.h``. It is not
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automatically executed. If you want to change the configuration
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settings associated with creating and mounting the ``/tmp``
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directory, then it will be necessary to re-generate this header file
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using the ``tools/mkromfsimg.sh`` script.
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The behavior of this script depends upon several things:
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#. The configuration settings then installed configuration.
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#. The ``genromfs`` tool(available from
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`http://romfs.sourceforge.net <http://romfs.sourceforge.net/>`__)
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or included within the NuttX buildroot toolchain. There is also a
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snapshot available in the NuttX tools repository
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`here <https://bitbucket.org/nuttx/tools/src/master/genromfs-0.5.2.tar.gz>`__.
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#. The ``xxd`` tool that is used to generate the C header files (xxd
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is a normal part of a complete Linux or Cygwin installation,
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usually as part of the ``vi`` package).
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#. The file ``apps/nshlib/rcS.template`` (OR, if
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``CONFIG_NSH_ARCHROMFS`` is defined
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``include/arch/board/rcs.template``.
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#. ``rcS.template``. The file ``apps/nshlib/rcS.template`` contains the
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general form of the ``rcS`` file; configured values are plugged into
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this template file to produce the final ``rcS`` file.
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To generate a custom ``rcS`` file a copy of ``rcS.template`` needs to
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be placed at ``tools/`` and changed according to the desired start-up
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behaviour. Running ``tools/mkromfsimg.h`` creates ``nsh_romfsimg.h``
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which needs to be copied to ``apps/nshlib`` OR if
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``CONFIG_NSH_ARCHROMFS`` is defined to
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``boards/<arch>/<chip>/<board>/include``.
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``rcS.template``. The default ``rcS.template``,
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``apps/nshlib/rcS.template``, generates the standard, default
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``apps/nshlib/nsh_romfsimg.h`` file.
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If ``CONFIG_NSH_ARCHROMFS`` is defined in the NuttX configuration file,
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then a custom, board-specific ``nsh_romfsimg.h`` file residing in
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``boards/<arch>/<chip>/<board>/include``\ will be used. NOTE when the OS
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is configured, ``include/arch/board`` will be linked to
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``boards/<arch>/<chip>/<board>/include``.
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All of the startup-behavior is contained in ``rcS.template``. The role
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of ``mkromfsimg.sh`` script is to (1) apply the specific configuration
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settings to ``rcS.template`` to create the final ``rcS``, and (2) to
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generate the header file ``nsh_romfsimg.h`` containing the ROMFS file
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system image. To do this, ``mkromfsimg.sh`` uses two tools that must be
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installed in your system:
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#. The ``genromfs`` tool that is used to generate the ROMFS file system
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image.
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#. The ``xxd`` tool that is used to create the C header file.
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