[Buildroot] [PATCH 13 of 13] manual/user guide/customization: add section on layered customization
Thomas De Schampheleire
patrickdepinguin at gmail.com
Thu Sep 18 19:39:36 UTC 2014
Inspired by some text in the 'project-specific patches' section, this patch
adds a separate section on layering customizations by providing multiple
post-build scripts, multiple rootfs overlays, etc.
Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire at gmail.com>
docs/manual/customize-directory-structure.txt | 51 +++++++++++++++++++
docs/manual/customize-patches.txt | 40 +--------------
2 files changed, 52 insertions(+), 39 deletions(-)
diff --git a/docs/manual/customize-directory-structure.txt b/docs/manual/customize-directory-structure.txt
@@ -56,3 +56,54 @@
Note: if you choose to place this structure outside of the Buildroot
tree using +BR2_EXTERNAL+, the <company> and possibly <boardname>
components may be superfluous and can be left out.
+==== Implementing layered customizations
+It is quite common for a user to have several related projects that partly
+need the same customizations. Instead of duplicating these
+customizations for each project, it is recommended to use a layered
+customization approach, as explained in this section.
+Almost all of the customization methods available in Buildroot, like
+post-build scripts and root filesystem overlays, accept a
+space-separated list of items. The specified items are always treated in
+order, from left to right. By creating more than one such item, one for
+the common customizations and another one for the really
+project-specific customizations, you can avoid unnecessary duplication.
+Each layer is typically embodied by a separate directory inside
++board/<company>/+. Depending on your projects, you could even introduce
+more than two layers.
+An example directory structure for where a user has two customization
+layers 'common' and 'fooboard' is:
+ +-- <company>/
+ +-- common/
+ | +-- post_build.sh
+ | +-- rootfs_overlay/
+ | | +-- ...
+ | +-- patches/
+ | +-- ...
+ +-- fooboard/
+ +-- linux.config
+ +-- busybox.config
+ +-- <other configuration files>
+ +-- post_build.sh
+ +-- rootfs_overlay/
+ | +-- ...
+ +-- patches/
+ +-- ...
+For example, if the user has the +BR2_GLOBAL_PATCH_DIR+ configuration
+option set as:
+then first the patches from the 'common' layer would be applied,
+followed by the patches from the 'fooboard' layer.
diff --git a/docs/manual/customize-patches.txt b/docs/manual/customize-patches.txt
@@ -10,13 +10,7 @@
The +BR2_GLOBAL_PATCH_DIR+ configuration option can be used to specify
a space separated list of one or more directories containing package
-patches. By specifying multiple global patch directories, a user could
-implement a layered approach to patches. This could be useful when a
-user has multiple boards that share a common processor architecture.
-It is often the case that a subset of patches for a package need to be
-shared between the different boards a user has. However, each board
-may require specific patches for the package that build on top of the
-common subset of patches.
For a specific version +<packageversion>+ of a specific package
+<packagename>+, patches are applied from +BR2_GLOBAL_PATCH_DIR+ as
@@ -63,35 +57,3 @@
patches that are applied after patches available in +BR2_GLOBAL_PATCH_DIR+,
as it is done from a post-patch hook of the Linux package.
-An example directory structure for where a user has multiple
-directories specified for +BR2_GLOBAL_PATCH_DIR+ may look like this:
-| +-- patches
-| +-- linux
-| | +-- linux-patch1.patch
-| | +-- linux-patch2.patch
-| +-- uboot
-| +-- foopkg
- +-- patches
- +-- linux
- | +-- linux-patch3.patch
- +-- uboot
- +-- foopkg
-If the user has the +BR2_GLOBAL_PATCH_DIR+ configuration option set as
-Then the patches would applied as follows for the Linux kernel:
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