Table of Contents

Variables

Auto override

# Create an automatic OVERRIDE for everything under src/
AUTO_OVERRIDES = $(notdir $(wildcard $(BR2_EXTERNAL)/src/*)))
do_override = $(1)_OVERRIDE_SRCDIR = $(BR2_EXTERNAL)/src/$(2)
$(foreach override,$(AUTO_OVERRIDES),\
        $(eval $(call do_override,$(call UPPERCASE,$(override)),$(override))))
 
#(this snippet is licensed GPLv2+). 
#by Arnout Vandecappelle (Essensium/Mind)

Variables

$(@D) which contains the directory in which the package source code has been uncompressed.
$(FOO_DIR) same as $(@D)
$(FOO_PKGDIR) contains the path to the directory containing the foo.mk and Config.in files.
$(HOST_DIR)
$(STAGING_DIR)
$(TARGET_DIR)

Cross compilation

Variables are defined in buildroot/package/Makefile.in

$(TARGET_CC) cross compiler gcc binary (i.e.: TARGET_CC=/home/user/project/out/host/usr/bin/ccache /home/user/project/out/host/usr/bin/arm-linux-gcc)
$(TARGET_AR) | | $(TARGET_AS) | | $(TARGET_CPP) | | $(TARGET_CXX) | | _FC _LD _NM | _RANLIB | _READELF | _OBJCOPY | | _OBJDUMP
$(TARGET_CC_NOCCACHE)
$(TARGET_CXX_NOCCACHE)
$(TARGET_CFLAGS) (i.e: TARGET_CFLAGS=-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -pipe -Os -g2)
$(TARGET_CPPFLAGS)
$(TARGET_CXXFLAGS)
$(TARGET_LDFLAGS)
$(TARGET_MAKE_ENV)

It overrides search path, to get cross compiler first. (i.e:PATH=“/home/user/project/out/host/bin:/home/user/project/out/host/ …) |

$(TARGET_DIR) device root filesystem (i.e: needed for installing packages into $(TARGET_DIR)/usr/bin)
$(STAGING_DIR) development target root filesystem (contains all needed libraries to build other packages, contains debug info and not stripped binary)

Additional variables (not needed in normal use)

$(CCACHE) full path to ccache binary or empty (i.e: CCACHE=/home/user/project/out/host/usr/bin/ccache)
$(TARGET_CROSS) prefix with full path to cross compiler (i.e: TARGET_CROSS=/home/user/project/out/host/usr/bin/arm-linux-)
$(ABI) gnueabi[hf] eabi[hf]
$(GNU_TARGET_NAME) GNU_TARGET_NAME=arm-buildroot-linux-uclibcgnueabi

Example

################################################################################
#
# genromfs
#
################################################################################

GENROMFS_VERSION = 0.5.2
GENROMFS_SITE = http://downloads.sourceforge.net/project/romfs/genromfs/$(GENROMFS_VERSION)
GENROMFS_LICENSE = GPLv2+
GENROMFS_LICENSE_FILES = COPYING

define GENROMFS_BUILD_CMDS
        $(TARGET_MAKE_ENV) $(MAKE) -C $(@D) \
                CC="$(TARGET_CC)" \
                CFLAGS="$(TARGET_CFLAGS)" \
                LDFLAGS="$(TARGET_LDFLAGS)"
endef

define GENROMFS_INSTALL_TARGET_CMDS
        $(TARGET_MAKE_ENV) $(MAKE) -C $(@D) PREFIX=$(TARGET_DIR) install
endef

define HOST_GENROMFS_BUILD_CMDS
        $(HOST_MAKE_ENV) $(MAKE) -C $(@D)
endef

define HOST_GENROMFS_INSTALL_CMDS
        $(HOST_MAKE_ENV) $(MAKE) -C $(@D) PREFIX=$(HOST_DIR) install
endef

$(eval $(generic-package))
$(eval $(host-generic-package))

LUA

LUAPOSIX_CONF_OPTS = --libdir="/usr/lib/lua/$(LUAINTERPRETER_ABIVER)" --datarootdir="/usr/share/lua/$(LUAINTERPRETER_ABIVER)"
define LUAEXPATUTILS_INSTALL_TARGET_CMDS
$(INSTALL) -m 0644 -D $(@D)/lua/doc.lua >$(TARGET_DIR)/usr/share/lua/$(LUAINTERPRETER_ABIVER)/lxp/doc.lua
endef
define LUA_MSGPACK_NATIVE_BUILD_CMDS
        $(TARGET_CC) $(TARGET_CFLAGS) -fPIC -shared -o $(@D)/msgpack.so $(@D)/mp.c
endef
 
define LUA_MSGPACK_NATIVE_INSTALL_TARGET_CMDS
        $(INSTALL) -m 755 -D $(@D)/msgpack.so \
                $(TARGET_DIR)/usr/lib/lua/$(LUAINTERPRETER_ABIVER)/msgpack.so
endef
 
$(eval $(generic-package))