rework patch model

At the Buildroot Developers Meeting (4-5 February 2013, in Brussels) a change
to the patch logic was discussed. See

http://elinux.org/Buildroot:DeveloperDaysFOSDEM2013

for details. In summary:

* For patches stored in the package directory, if
  package/<pkg>/<version>/ does exist, apply package/<pkg>/<version>/*.patch,
  otherwise, apply package/<pkg>/*.patch
* For patches stored in the global patches directory, if
  $(GLOBAL_PATCH_DIR)/<pkg>/<version>/ does exist, apply
  $(GLOBAL_PATCH_DIR)/<pkg>/<version>/*.patch, otherwise, apply
  $(GLOBAL_PATCH_DIR)/<pkg>/*.patch

This patch adds the new BR2_GLOBAL_PATCH_DIR configuration item, and reworks
the generic package infrastructure to implement the new patch logic.

[Peter: fixup doc nits as pointed out by Thomas]
Signed-off-by: Simon Dawson <spdawson@gmail.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

1 files changed, 23 insertions, 0 deletions

diff --git a/docs/manual/customize-packages.txt b/docs/manual/customize-packages.txt
new file mode 100644
index 000000000..1820c544e
--- /dev/null
+++ b/docs/manual/customize-packages.txt
@@ -0,0 +1,23 @@
+// -*- mode:doc -*- ;
+
+[[packages-custom]]
+Customizing packages
+~~~~~~~~~~~~~~~~~~~~
+
+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.
+
+For a specific version <packageversion> of a specific package <packagename>,
+patches are applied as follows.
+
+First, the default Buildroot patch set for the package is applied.
+
+If the directory +$(BR2_GLOBAL_PATCH_DIR)/<packagename>/<packageversion>+
+exists, then all +*.patch+ files in the directory will be applied.
+
+Otherwise, if the directory +$(BR2_GLOBAL_PATCH_DIR)/<packagename>+
+exists, then all +*.patch+ files in the directory will be applied.