@@ -8,16 +8,90 @@ It is sometimes useful to apply 'extra' patches to packages - over and
above those provided in Buildroot. This might be used to support custom
features in a project, for example, or when working on a new architecture.
-The +BR2_GLOBAL_PATCH_DIR+ configuration file option can be
-used to specify a directory containing global package patches.
+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 as follows.
+For a specific version +<packageversion>+ of a specific package
++<packagename>+, patches are applied from +BR2_GLOBAL_PATCH_DIR+ as
+follows:
-First, the default Buildroot patch set for the package is applied.
+. For every directory - +<global-patch-dir>+ - that exists in
+ +BR2_GLOBAL_PATCH_DIR+, a +<package-patch-dir>+ will be determined as
+ follows:
++
+* +<global-patch-dir>/<packagename>/<packageversion>/+ if the
+ directory exists.
++
+* Otherwise, +<global-patch-dir>/<packagename>+ if the directory
+ exists.
-If the directory +$(BR2_GLOBAL_PATCH_DIR)/<packagename>/<packageversion>+
-exists, then all +*.patch+ files in the directory will be applied.
+. Patches will then be applied from a +<package-patch-dir>+ as
+ follows:
++
+* If a +series+ file exists in the package directory, then patches are
+ applied according to the +series+ file;
++
+* Otherwise, patch files matching +<packagename>-*.patch+
+ are applied in alphabetical order.
+ So, to ensure they are applied in the right order, it is highly
+ recommended to name the patch files like this:
+ +<packagename>-<number>-<description>.patch+, where +<number>+
+ refers to the 'apply order'.
-Otherwise, if the directory +$(BR2_GLOBAL_PATCH_DIR)/<packagename>+
-exists, then all +*.patch+ files in the directory will be applied.
+For information about how patches are applied for a package, see
+xref:patch-apply-order[]
+
+The +BR2_GLOBAL_PATCH_DIR+ option is the preferred method for
+specifying a custom patch directory for packages. It can be used to
+specify a patch directory for any package in buildroot. It should also
+be used in place of the custom patch directory options that are
+available for packages such as U-Boot and Barebox. By doing this, it
+will allow a user to manage their patches from one top-level
+directory.
+
+The exception to +BR2_GLOBAL_PATCH_DIR+ being the preferred method for
+specifying custom patches is +BR2_LINUX_KERNEL_PATCH+.
++BR2_LINUX_KERNEL_PATCH+ should be used to specify kernel patches that
+are available at an URL. *Note:* +BR2_LINUX_KERNEL_PATCHES+ are applied
+after patches available in +BR2_GLOBAL_PATCH_DIR+ as it is a patch
+post-hook step for the Linux package.
+
+An example directory structure for where a user has multiple
+directories specified for +BR2_GLOBAL_PATCH_DIR+ may look like this:
+
+-----
+board/
++-- common-fooarch
+| +-- patches
+| +-- linux
+| | +-- linux-patch1.patch
+| | +-- linux-patch2.patch
+| +-- u-boot
+| +-- foopkg
++-- fooarch-board
+ +-- patches
+ +-- linux
+ | +-- linux-patch3.patch
+ +-- u-boot
+ +-- foopkg
+-----
+
+If the user has the +BR2_GLOBAL_PATCH_DIR+ configuration option set as
+follows:
+
+-----
+BR2_GLOBAL_PATCH_DIR="board/common-fooarch board/fooarch-board"
+-----
+
+Then the patches would applied as follows for the Linux kernel:
+
+. board/common-fooarch/patches/linux/linux-patch1.patch
+. board/common-fooarch/patches/linux/linux-patch2.patch
+. board/fooarch-board/patches/linux/linux-patch3.patch
@@ -50,10 +50,11 @@ Global patch directory
^^^^^^^^^^^^^^^^^^^^^^
The +BR2_GLOBAL_PATCH_DIR+ configuration file option can be
-used to specify a directory containing global package patches. See
-xref:packages-custom[] for details.
-
+used to specify a space separated list of one or more directories
+containing global package patches. See xref:packages-custom[] for
+details.
+[[patch-apply-order]]
How patches are applied
~~~~~~~~~~~~~~~~~~~~~~~
@@ -64,19 +65,24 @@ How patches are applied
. If +<packagename>_PATCH+ is defined, then patches from these
tarballs are applied;
-. If there are some +*.patch+ files in the package directory or in the
- a package subdirectory named +<packageversion>+, then:
+. If there are some +*.patch+ files in the package's Buildroot
+ directory or in a package subdirectory named +<packageversion>+,
+ then:
+
* If a +series+ file exists in the package directory, then patches are
applied according to the +series+ file;
+
* Otherwise, patch files matching +<packagename>-*.patch+
are applied in alphabetical order.
- So, to ensure they are applied in the right order, it is hightly
- recommended to named the patch files like this:
+ So, to ensure they are applied in the right order, it is highly
+ recommended to name the patch files like this:
+<packagename>-<number>-<description>.patch+, where +<number>+
refers to the 'apply order'.
+. If +BR2_GLOBAL_PATCH_DIR+ is defined, the directories will be
+ enumerated in the order they are specified. The patches are applied
+ as described in the previous step.
+
. Run the +<packagename>_POST_PATCH_HOOKS+ commands if defined.
If something goes wrong in the steps _3_ or _4_, then the build fails.
Updating the documentation to reflect that multiple directories can now be specified for BR2_GLOBAL_PATCH_DIR. Along with giving an example use case of how to use multiple global patch directories. Signed-off-by: Ryan Barnett <rjbarnet@rockwellcollins.com> Cc: Thomas De Schampheleire <patrickdepinguin@gmail.com> Cc: Arnout Vandecappelle <arnout@mind.be> --- Changes v4 -> v5: - Fixed minor wording issue and spelling (suggested by Thomas D) Changes v3 -> v4: - Fixed minor spelling mistakes and wording (suggested by Arnout) - Reword section about order that patches are applied along with making it clearer about when to use BR2_GLOBAL_PATCH_DIR (suggested by Arnout) Changes v2 -> v3: - None Changes v1 -> v2: - Fixed minor spelling mistakes and wording (suggested by Thomas D) --- docs/manual/customize-packages.txt | 92 ++++++++++++++++++++++++++++++++---- docs/manual/patch-policy.txt | 20 +++++--- 2 files changed, 96 insertions(+), 16 deletions(-)