path: root/Makefile
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authorGravatar Thomas Petazzoni <thomas.petazzoni@free-electrons.com>2013-12-05 20:11:10 +0100
committerGravatar Peter Korsgaard <peter@korsgaard.com>2013-12-08 22:38:13 +0100
commita4239f7fd1053c11bf4bb8bbc98cbe4b513f2d47 (patch)
tree4aaedd99fea7c588af8df3fcbd9ddfd338b14e9f /Makefile
parentedeb7d53978f20acc2306b71bc818e81298a68b3 (diff)
core: introduce the BR2_EXTERNAL variable
This commit introduces the BR2_EXTERNAL environment variable, which will allow to keep Buildroot customization (board-specific configuration files or root filesystem overlays, package Config.in and makefiles, as well as defconfigs) outside of the Buildroot tree. This commit only introduces the variable itself, and ensures that it is available within Config.in options. This allows us to use $BR2_EXTERNAL in a 'source' statement in Config.in. Following patches extend the usage of BR2_EXTERNAL to other areas (packages and defconfigs). In details, this commit: * Introduces the BR2_EXTERNAL Kconfig option. This option has no prompt, and is therefore not visible to the user and also not stored in the .config file. It is automatically set to the value of the BR2_EXTERNAL environment variable. The only purpose of this BR2_EXTERNAL Kconfig option is to allow $BR2_EXTERNAL to be properly expanded when used inside Kconfig source statements. * Calculates the BR2_EXTERNAL value to use. If passed on the command line, then this value is taken in priority, and saved to a .br-external hidden file in the output directory. If not passed on the command line, then we read the .br-external file from the output directory. This allows the user to not pass the BR2_EXTERNAL value at each make invocation. If no BR2_EXTERNAL value is passed, we define it to support/dummy-external, so that the kconfig code finds an existing $(BR2_EXTERNAL)/package/Config.in file to include. * Passes the BR2_EXTERNAL into the *config environment, so that its value is found when parsing/evaluating Config.in files and .config values. Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Acked-by: Ryan Barnett <rjbarnet@rockwellcollins.com> Tested-by: "Samuel Martin" <s.martin49@gmail.com> Acked-by: "Samuel Martin" <s.martin49@gmail.com> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Diffstat (limited to 'Makefile')
1 files changed, 25 insertions, 1 deletions
diff --git a/Makefile b/Makefile
index 6adacd97ad..f92fd9b2c3 100644
--- a/Makefile
+++ b/Makefile
@@ -99,6 +99,29 @@ export CDPATH:=
BASE_DIR := $(shell mkdir -p $(O) && cd $(O) >/dev/null && pwd)
$(if $(BASE_DIR),, $(error output directory "$(O)" does not exist))
+# Handling of BR2_EXTERNAL.
+# The value of BR2_EXTERNAL is stored in .br-external in the output directory.
+# On subsequent invocations of make, it is read in. It can still be overridden
+# on the command line, therefore the file is re-created every time make is run.
+# When BR2_EXTERNAL is not set, the .br-external file is removed and we point
+# to support/dummy-external. This makes sure we can unconditionally include the
+# Config.in and external.mk from the BR2_EXTERNAL directory. In this case,
+# override is necessary so the user can clear BR2_EXTERNAL from the command
+# line, but the dummy path is still used internally.
+BR2_EXTERNAL_FILE = $(BASE_DIR)/.br-external
+-include $(BR2_EXTERNAL_FILE)
+ifeq ($(BR2_EXTERNAL),)
+ override BR2_EXTERNAL = support/dummy-external
+ $(shell rm -f $(BR2_EXTERNAL_FILE))
+ $(shell echo BR2_EXTERNAL ?= $(BR2_EXTERNAL) > $(BR2_EXTERNAL_FILE))
@@ -631,7 +654,8 @@ COMMON_CONFIG_ENV = \
KCONFIG_AUTOCONFIG=$(BUILD_DIR)/buildroot-config/auto.conf \
KCONFIG_AUTOHEADER=$(BUILD_DIR)/buildroot-config/autoconf.h \
KCONFIG_TRISTATE=$(BUILD_DIR)/buildroot-config/tristate.config \
xconfig: $(BUILD_DIR)/buildroot-config/qconf outputmakefile
@mkdir -p $(BUILD_DIR)/buildroot-config