--- /dev/null
+// -*- mode:doc; -*-
+// vim: set syntax=asciidoc:
+
+=== Infrastructure for CMake-based packages
+
+[[cmake-package-tutorial]]
+
+==== +cmake-package+ tutorial
+
+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:
+07: LIBFOO_VERSION = 1.0
+08: LIBFOO_SOURCE = libfoo-$(LIBFOO_VERSION).tar.gz
+09: LIBFOO_SITE = http://www.foosoftware.org/download
+10: LIBFOO_INSTALL_STAGING = YES
+11: LIBFOO_INSTALL_TARGET = NO
+12: LIBFOO_CONF_OPTS = -DBUILD_DEMOS=ON
+13: LIBFOO_DEPENDENCIES = libglib2 host-pkgconf
+14:
+15: $(eval $(cmake-package))
+------------------------
+
+On line 7, we declare the version of the package.
+
+On line 8 and 9, we declare the name of the tarball (xz-ed tarball recommended)
+and the location of the tarball on the Web. Buildroot will automatically
+download the tarball from this location.
+
+On line 10, 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 11, we tell Buildroot to not install the package to the
+target directory. This directory contains what will become the root
+filesystem running on the target. For purely static libraries, it is
+not necessary to install them in the target directory because they will
+not be used at runtime. By default, target installation is enabled; setting
+this variable to NO is almost never needed. Also by default, packages are
+installed in this location using the +make install+ command.
+
+On line 12, we tell Buildroot to pass custom options to CMake when it is
+configuring the package.
+
+On line 13, we declare our dependencies, so that they are built
+before the build process of our package starts.
+
+Finally, on line line 15, we invoke the +cmake-package+
+macro that generates all the Makefile rules that actually allows the
+package to be built.
+
+[[cmake-package-reference]]
+
+==== +cmake-package+ reference
+
+The main macro of the CMake package infrastructure is
++cmake-package+. It is similar to the +generic-package+ macro. The ability to
+have target and host packages is also available, with the
++host-cmake-package+ macro.
+
+Just like the generic infrastructure, the CMake infrastructure works
+by defining a number of variables before calling the +cmake-package+
+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_OPTS+, to specify additional configure options to pass
+ to CMake. By default, empty. A number of common CMake options are
+ set by the +cmake-package+ infrastructure; so it is normally not
+ necessary to set them in the package's +*.mk+ file unless you want
+ to override them:
+
+** +CMAKE_BUILD_TYPE+ is driven by +BR2_ENABLE_DEBUG+;
+** +CMAKE_INSTALL_PREFIX+;
+** +BUILD_SHARED_LIBS+ is driven by +BR2_STATIC_LIBS+;
+** +BUILD_DOC+, +BUILD_DOCS+ are disabled;
+** +BUILD_EXAMPLE+, +BUILD_EXAMPLES+ are disabled;
+** +BUILD_TEST+, +BUILD_TESTS+, +BUILD_TESTING+ are disabled.
+
+* +LIBFOO_SUPPORTS_IN_SOURCE_BUILD = NO+ should be set when the package
+ cannot be built inside the source tree but needs a separate build
+ directory.
+
+* +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=$(MAKE1)+.
+
+* +LIBFOO_MAKE_ENV+, to specify additional environment variables to
+ pass to make in the build step. These are passed before the +make+
+ command. By default, empty.
+
+* +LIBFOO_MAKE_OPTS+, to specify additional variables to pass to make
+ in the build step. These are passed after the +make+ command. By
+ default, empty.
+
+* +LIBFOO_INSTALL_STAGING_OPTS+ contains the make options used to
+ install the package to the staging directory. By default, the value
+ is +DESTDIR=$(STAGING_DIR) install+, which is correct for most
+ CMake packages. It is still possible to override it.
+
+* +LIBFOO_INSTALL_TARGET_OPTS+ 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.
+
+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:
+
+* By adding a post-operation hook (after extract, patch, configure,
+ build or install). See xref:hooks[] for details.
+
+* By overriding one of the steps. For example, even if the CMake
+ infrastructure is used, if the package +.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.
Code Review / packages / trusty / cirros-testvm.git / blobdiff