First, let's see how to write a .mk file for a CMake-based
+ package, with an example :
+01: ############################################################# +02: # +03: # libfoo +04: # +05: ############################################################# +06: LIBFOO_VERSION = 1.0 +07: LIBFOO_SOURCE = libfoo-$(LIBFOO_VERSION).tar.gz +08: LIBFOO_SITE = http://www.foosoftware.org/download +09: LIBFOO_INSTALL_STAGING = YES +10: LIBFOO_INSTALL_TARGET = YES +11: LIBFOO_CONF_OPT = -DBUILD_DEMOS=ON +12: LIBFOO_DEPENDENCIES = libglib2 host-pkg-config +13: +14: $(eval $(call CMAKETARGETS,package,libfoo)) ++ +
On line 6, we declare the version of the package.
+ +On line 7 and 8, we declare the name of the tarball and the location + of the tarball on the Web. Buildroot will automatically download the + tarball from this location.
+ +On line 9, we tell Buildroot to install the package to the staging
+ directory. The staging directory, located in output/staging/
+ is the directory where all the packages are installed, including their
+ development files, etc. By default, packages are not installed to the
+ staging directory, since usually, only libraries need to be installed in
+ the staging directory: their development files are needed to compile
+ other libraries or applications depending on them. Also by default, when
+ staging installation is enabled, packages are installed in this location
+ using the make install command.
On line 10, we tell Buildroot to also install the package to the
+ target directory. This directory contains what will become the root
+ filesystem running on the target. Usually, we try not to install header
+ files and to install stripped versions of the binary. By default, target
+ installation is enabled, so in fact, this line is not strictly
+ necessary. Also by default, packages are installed in this location
+ using the make install command.
On line 11, we tell Buildroot to pass custom options to CMake when it is + configuring the package.
+ +On line 12, we declare our dependencies, so that they are built + before the build process of our package starts.
+ +Finally, on line line 14, we invoke the CMAKETARGETS
+ macro that generates all the Makefile rules that actually allows the
+ package to be built.
The main macro of the CMake package infrastructure is
+ CMAKETARGETS. It has the same number of arguments and the
+ same semantic as the GENTARGETS macro, which is the main
+ macro of the generic package infrastructure. For CMake packages, the
+ ability to have target and host packages is also available.
Just like the generic infrastructure, the CMake infrastructure
+ works by defining a number of variables before calling the
+ CMAKETARGETS macro.
First, all the package metadata information variables that exist in the
+ generic infrastructure also exist in the CMake infrastructure:
+ LIBFOO_VERSION, LIBFOO_SOURCE,
+ LIBFOO_PATCH, LIBFOO_SITE,
+ LIBFOO_SUBDIR, LIBFOO_DEPENDENCIES,
+ LIBFOO_INSTALL_STAGING, LIBFOO_INSTALL_TARGET.
A few additional variables, specific to the CMake infrastructure, + can also be defined. Many of them are only useful in very specific + cases, typical packages will therefore only use a few of them.
+ +LIBFOO_SUBDIR may contain the name of a subdirectory
+ inside the package that contains the main CMakeLists.txt file. This is
+ useful, if for example, the main CMakeLists.txt file is not at the root
+ of the tree extracted by the tarball. If HOST_LIBFOO_SUBDIR
+ is not specified, it defaults to LIBFOO_SUBDIR.LIBFOO_CONF_ENV, to specify additional environment
+ variables to pass to CMake. By default, empty.LIBFOO_CONF_OPT, to specify additional configure
+ options to pass to CMake. By default, empty.LIBFOO_MAKE, to specify an alternate make
+ command. This is typically useful when parallel make is enabled in
+ the configuration (using BR2_JLEVEL) but that this
+ feature should be disabled for the given package, for one reason or
+ another. By default, set to $(MAKE). If parallel building
+ is not supported by the package, then it should be set to
+ LIBFOO_MAKE=$(MAKE1).LIBFOO_MAKE_ENV, to specify additional environment
+ variables to pass to make in the build step. These are passed before
+ the make command. By default, empty.LIBFOO_MAKE_OPT, to specify additional variables to
+ pass to make in the build step. These are passed after the
+ make command. By default, empty.LIBFOO_INSTALL_STAGING_OPT contains the make options
+ used to install the package to the staging directory. By default, the
+ value is DESTDIR=$$(STAGING_DIR) install, which is
+ correct for most CMake packages. It is still possible to override
+ it.LIBFOO_INSTALL_TARGET_OPT contains the make options
+ used to install the package to the target directory. By default, the
+ value is DESTDIR=$$(TARGET_DIR) install. The default
+ value is correct for most CMake packages, but it is still possible
+ to override it if needed.LIBFOO_CLEAN_OPT contains the make options used to
+ clean the package. By default, the value is clean.With the CMake infrastructure, all the steps required to build + and install the packages are already defined, and they generally work + well for most CMake-based packages. However, when required, it is + still possible to customize what is done in any particular step:
+ +.mk file defines its
+ own LIBFOO_CONFIGURE_CMDS variable, it will be used
+ instead of the default CMake one. However, using this method
+ should be restricted to very specific cases. Do not use it in the
+ general case.NOTE: new manual makefiles should not be created, and existing - manual makefiles should be converted either to the generic - infrastructure or the autotools infrastructure. This section is only - kept to document the existing manual makefiles and to help understand - how they work.
+ manual makefiles should be converted either to the generic, autotools + or cmake infrastructure. This section is only kept to document the existing + manual makefiles and to help understand how they work.01: #############################################################