[Buildroot] [PATCH for 2014.08] Manual improvements part 5
Thomas De Schampheleire
patrickdepinguin at gmail.com
Sun Aug 31 12:08:23 UTC 2014
Sorry, this was with wrong subject... See next patch.
On Sun, Aug 31, 2014 at 2:06 PM, Thomas De Schampheleire
<patrickdepinguin at gmail.com> wrote:
> This patch reworks the section on root filesystem customization as follows:
> - use labeled list instead of bulleted list to clarify the different methods
> - move rootfs overlay and post-build scripts to the top and label them as
> recommended.
> - split post-image to a separate section, as it is not related to the target
> filesystem customization
> - line up post-build and post-image explanations, for example regarding
> working directory of the script
> - general expansion of some of the explanation
> - general rewording
>
> Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire at gmail.com>
>
> ---
> docs/manual/customize-rootfs.txt | 153 ++++++++++++++++--------------
> docs/manual/customize.txt | 2 +
> 2 files changed, 84 insertions(+), 71 deletions(-)
>
> diff --git a/docs/manual/customize-rootfs.txt b/docs/manual/customize-rootfs.txt
> --- a/docs/manual/customize-rootfs.txt
> +++ b/docs/manual/customize-rootfs.txt
> @@ -4,85 +4,96 @@
> [[rootfs-custom]]
> === Customizing the generated target filesystem
>
> -Besides changing one or another configuration through +make *config+,
> -there are a few ways to customize the resulting target filesystem.
> +Besides changing the configuration through +make *config+,
> +there are a few other ways to customize the resulting target filesystem.
>
> -* Customize the target filesystem directly and rebuild the image. The
> - target filesystem is available under +output/target/+. You can
> - simply make your changes here and run make afterwards - this will
> - rebuild the target filesystem image. This method allows you to do
> - anything to the target filesystem, but if you decide to completely
> - rebuild your toolchain and tools, these changes will be lost. This
> - solution is therefore only useful for quick tests only: _changes do
> - not survive the +make clean+ command_. Once you have validated your
> - changes, you should make sure that they will persist after a +make
> - clean+ by using one of the following methods.
> +The two recommended methods, which can co-exist, are root filesystem
> +overlay(s) and post build script(s).
>
> -* Create a filesystem overlay: a tree of files that are copied directly
> - over the target filesystem after it has been built. Set
> - +BR2_ROOTFS_OVERLAY+ to the top of the tree. +.git+, +.svn+, +.hg+
> - directories, +.empty+ files and files ending with +~+ are excluded.
> - _Among these first 3 methods, this one should be preferred_.
> +Root filesystem overlays (+BR2_ROOTFS_OVERLAY+)::
> ++
> +A filesystem overlay is a tree of files that is copied directly
> + over the target filesystem after it has been built. To enable this
> + feature, set config option +BR2_ROOTFS_OVERLAY+ (in the +System
> + configuration+ menu) to the root of the overlay. You can even specify
> + multiple overlays, space-separated. If you specify a relative path,
> + it will be relative to the root of the Buildroot tree. Hidden
> + directories of version control systems, like +.git+, +.svn+, +.hg+,
> + etc., files called +.empty+ and files ending in +~+ are excluded from
> + the copy.
>
> -* In the Buildroot configuration, you can specify the paths to one or
> - more *post-build scripts*. These scripts are called in the given order,
> - 'after' Buildroot builds all the selected software, but 'before' the
> - rootfs images are assembled. The +BR2_ROOTFS_POST_BUILD_SCRIPT+ allows
> - you to specify the location of your post-build scripts. This option can be
> - found in the +System configuration+ menu. The destination root
> - filesystem folder is given as the first argument to these scripts,
> - and these scripts can then be used to remove or modify any file in your
> +Post-build scripts (+BR2_ROOTFS_POST_BUILD_SCRIPT+)::
> ++
> +Post-build scripts are shell scripts called 'after' Buildroot builds
> + all the selected software, but 'before' the rootfs images are
> + assembled. To enable this feature, specify a space-separated list of
> + post-build scripts in config option +BR2_ROOTFS_POST_BUILD_SCRIPT+ (in
> + the +System configuration+ menu). If you specify a relative path, it
> + will be relative to the root of the Buildroot tree.
> ++
> +Using post-build scripts, you can remove or modify any file in your
> target filesystem. You should, however, use this feature with care.
> Whenever you find that a certain package generates wrong or unneeded
> files, you should fix that package rather than work around it with some
> post-build cleanup scripts.
> - You may also use these variables in your post-build script:
> - - +BR2_CONFIG+: the path to the Buildroot .config file
> - - +HOST_DIR+, +STAGING_DIR+, +TARGET_DIR+: see
> - xref:generic-package-reference[]
> - - +BUILD_DIR+: the directory where packages are extracted and built
> - - +BINARIES_DIR+: the place where all binary files (aka images) are
> - stored
> - - +BASE_DIR+: the base output directory
> ++
> +The post-build scripts are run with the main Buildroot tree as current
> + working directory. The path to the target filesystem is passed as the
> + first argument to each script. If the config option
> + +BR2_ROOTFS_POST_SCRIPT_ARGS+ is not empty, these arguments will be
> + passed to the script too. All the scripts will be passed the exact
> + same set of arguments, it is not possible to pass different sets of
> + arguments to each script.
> ++
> +In addition, you may also use these environment variables:
>
> -* Create your own 'target skeleton'. You can start with the default
> - skeleton available under +system/skeleton+ and then customize it to
> - suit your needs. The +BR2_ROOTFS_SKELETON_CUSTOM+ and
> - +BR2_ROOTFS_SKELETON_CUSTOM_PATH+ will allow you to specify the
> - location of your custom skeleton. These options can be found in the
> - +System configuration+ menu. At build time, the contents of the
> - skeleton are copied to output/target before any package
> - installation. Note that this method is *not recommended*, as it
> - duplicates the entire skeleton, which prevents from taking advantage
> - of the fixes or improvements brought to the default Buildroot
> - skeleton. The recommended method is to use the _post-build scripts_
> - mechanism described in the previous item.
> + - +BR2_CONFIG+: the path to the Buildroot .config file
> + - +HOST_DIR+, +STAGING_DIR+, +TARGET_DIR+: see
> + xref:generic-package-reference[]
> + - +BUILD_DIR+: the directory where packages are extracted and built
> + - +BINARIES_DIR+: the place where all binary files (aka images) are
> + stored
> + - +BASE_DIR+: the base output directory
>
> -Note also that you can use the *post-image scripts*
> -if you want to perform some specific actions 'after' all
> -filesystem images have been created (for example to automatically
> -extract your root filesystem tarball in a location exported by your
> -NFS server, or to create a special firmware image that bundles your
> -root filesystem and kernel image, or any other custom action), you can
> -specify a space-separated list of scripts in the
> -+BR2_ROOTFS_POST_IMAGE_SCRIPT+ configuration option. This option can be
> -found in the +System configuration+ menu as well.
> +Below two more methods of customizing the target filesystem are
> +described, but they are not recommended.
>
> -Each of those scripts will be called with the path to the +images+
> -output directory as first argument, and will be executed with the main
> -Buildroot source directory as the current directory. Those scripts will
> -be executed as the user that executes Buildroot, which should normally
> -not be the root user. Therefore, any action requiring root permissions
> -in one of these _post-image scripts_ will require special handling
> -(usage of fakeroot or sudo), which is left to the script developer.
> +Direct modification of the target filesystem::
> ++
> +For temporary modifications, you can modify the target filesystem
> + directly and rebuild the image. The target filesystem is available
> + under +output/target/+. After making your changes, run +make+ to
> + rebuild the target filesystem image.
> ++
> +This method allows you to do anything to the target filesystem, but if
> + you need to clean your Buildroot tree using +make clean+, these
> + changes will be lost. Such cleaning is necessary in several cases,
> + refer to xref:full-rebuild[] for details. This solution is therefore
> + only useful for quick tests: _changes do not survive the +make clean+
> + command_. Once you have validated your changes, you should make sure
> + that they will persist after a +make clean+, using a root filesystem
> + overlay or a post-build script.
>
> -Just like for the _post-build scripts_ mentioned above, you also have
> -access to the following environment variables from your _post-image
> -scripts_: +BR2_CONFIG+, +BUILD_DIR+, +HOST_DIR+, +STAGING_DIR+,
> -+TARGET_DIR+, +BINARIES_DIR+ and +BASE_DIR+.
> -
> -Additionally, each of the +BR2_ROOTFS_POST_BUILD_SCRIPT+ and
> -+BR2_ROOTFS_POST_IMAGE_SCRIPT+ scripts will be passed the arguments
> -specified in +BR2_ROOTFS_POST_SCRIPT_ARGS+ (if that is not empty).
> -All the scripts will be passed the exact same set of arguments, it
> -is not possible to pass different sets of arguments to each script.
> +Custom target skeleton (+BR2_ROOTFS_SKELETON_CUSTOM+)::
> ++
> +The root filesystem image is created from a target skeleton, on top of
> + which all packages install their files. The skeleton is copied to the
> + target directory +output/target+ before any package is built and
> + installed. The default target skeleton provides the standard Unix
> + filesystem layout and some basic init scripts and configuration files.
> ++
> +If the default skeleton (available under +system/skeleton+) does not
> + match your needs, you would typically use a root filesystem overlay or
> + post-build script to adapt it. However, if the default skeleton is
> + entirely different than what you need, using a custom skeleton may be
> + more suitable.
> ++
> +To enable this feature, enable config option
> + +BR2_ROOTFS_SKELETON_CUSTOM+ and set +BR2_ROOTFS_SKELETON_CUSTOM_PATH+
> + to the path of your custom skeleton. Both options are available in the
> + +System configuration+ menu. If you specify a relative path, it will
> + be relative to the root of the Buildroot tree.
> ++
> +This method is not recommended because it duplicates the entire
> + skeleton, which prevents taking advantage of the fixes or improvements
> + brought to the default skeleton in later Buildroot releases.
> diff --git a/docs/manual/customize.txt b/docs/manual/customize.txt
> --- a/docs/manual/customize.txt
> +++ b/docs/manual/customize.txt
> @@ -40,6 +40,8 @@
>
> include::customize-rootfs.txt[]
>
> +include::customize-post-image.txt[]
> +
> include::customize-store.txt[]
>
> include::customize-packages.txt[]
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