665e13c85e
Since a while, the semantic of BR2_PREFER_STATIC_LIB has been changed from "prefer static libraries when possible" to "use only static libraries". The former semantic didn't make much sense, since the user had absolutely no control/idea of which package would use static libraries, and which packages would not. Therefore, for quite some time, we have been starting to enforce that BR2_PREFER_STATIC_LIB should really build everything with static libraries. As a consequence, this patch renames BR2_PREFER_STATIC_LIB to BR2_STATIC_LIBS, and adjust the Config.in option accordingly. This also helps preparing the addition of other options to select shared, shared+static or just static. Note that we have verified that this commit can be reproduced by simply doing a global rename of BR2_PREFER_STATIC_LIB to BR2_STATIC_LIBS plus adding BR2_PREFER_STATIC_LIB to Config.in.legacy. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
149 lines
6.2 KiB
Plaintext
149 lines
6.2 KiB
Plaintext
// -*- mode:doc; -*-
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// vim: set syntax=asciidoc:
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=== Infrastructure for CMake-based packages
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[[cmake-package-tutorial]]
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==== +cmake-package+ tutorial
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First, let's see how to write a +.mk+ file for a CMake-based package,
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with an example :
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------------------------
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01: ################################################################################
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02: #
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03: # libfoo
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04: #
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05: ################################################################################
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06:
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07: LIBFOO_VERSION = 1.0
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08: LIBFOO_SOURCE = libfoo-$(LIBFOO_VERSION).tar.gz
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09: LIBFOO_SITE = http://www.foosoftware.org/download
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10: LIBFOO_INSTALL_STAGING = YES
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11: LIBFOO_INSTALL_TARGET = NO
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12: LIBFOO_CONF_OPTS = -DBUILD_DEMOS=ON
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13: LIBFOO_DEPENDENCIES = libglib2 host-pkgconf
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14:
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15: $(eval $(cmake-package))
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------------------------
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On line 7, we declare the version of the package.
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On line 8 and 9, we declare the name of the tarball (xz-ed tarball recommended)
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and the location of the tarball on the Web. Buildroot will automatically
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download the tarball from this location.
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On line 10, we tell Buildroot to install the package to the staging
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directory. The staging directory, located in +output/staging/+
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is the directory where all the packages are installed, including their
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development files, etc. By default, packages are not installed to the
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staging directory, since usually, only libraries need to be installed in
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the staging directory: their development files are needed to compile
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other libraries or applications depending on them. Also by default, when
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staging installation is enabled, packages are installed in this location
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using the +make install+ command.
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On line 11, we tell Buildroot to not install the package to the
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target directory. This directory contains what will become the root
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filesystem running on the target. For purely static libraries, it is
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not necessary to install them in the target directory because they will
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not be used at runtime. By default, target installation is enabled; setting
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this variable to NO is almost never needed. Also by default, packages are
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installed in this location using the +make install+ command.
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On line 12, we tell Buildroot to pass custom options to CMake when it is
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configuring the package.
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On line 13, we declare our dependencies, so that they are built
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before the build process of our package starts.
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Finally, on line line 15, we invoke the +cmake-package+
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macro that generates all the Makefile rules that actually allows the
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package to be built.
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[[cmake-package-reference]]
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==== +cmake-package+ reference
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The main macro of the CMake package infrastructure is
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+cmake-package+. It is similar to the +generic-package+ macro. The ability to
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have target and host packages is also available, with the
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+host-cmake-package+ macro.
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Just like the generic infrastructure, the CMake infrastructure works
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by defining a number of variables before calling the +cmake-package+
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macro.
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First, all the package metadata information variables that exist in
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the generic infrastructure also exist in the CMake infrastructure:
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+LIBFOO_VERSION+, +LIBFOO_SOURCE+, +LIBFOO_PATCH+, +LIBFOO_SITE+,
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+LIBFOO_SUBDIR+, +LIBFOO_DEPENDENCIES+, +LIBFOO_INSTALL_STAGING+,
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+LIBFOO_INSTALL_TARGET+.
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A few additional variables, specific to the CMake infrastructure, can
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also be defined. Many of them are only useful in very specific cases,
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typical packages will therefore only use a few of them.
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* +LIBFOO_SUBDIR+ may contain the name of a subdirectory inside the
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package that contains the main CMakeLists.txt file. This is useful,
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if for example, the main CMakeLists.txt file is not at the root of
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the tree extracted by the tarball. If +HOST_LIBFOO_SUBDIR+ is not
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specified, it defaults to +LIBFOO_SUBDIR+.
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* +LIBFOO_CONF_ENV+, to specify additional environment variables to
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pass to CMake. By default, empty.
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* +LIBFOO_CONF_OPTS+, to specify additional configure options to pass
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to CMake. By default, empty. A number of common CMake options are
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set by the +cmake-package+ infrastructure; so it is normally not
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necessary to set them in the package's +*.mk+ file unless you want
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to override them:
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** +CMAKE_BUILD_TYPE+ is driven by +BR2_ENABLE_DEBUG+;
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** +CMAKE_INSTALL_PREFIX+;
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** +BUILD_SHARED_LIBS+ is driven by +BR2_STATIC_LIBS+;
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** +BUILD_DOC+, +BUILD_DOCS+ are disabled;
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** +BUILD_EXAMPLE+, +BUILD_EXAMPLES+ are disabled;
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** +BUILD_TEST+, +BUILD_TESTS+, +BUILD_TESTING+ are disabled.
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* +LIBFOO_MAKE+, to specify an alternate +make+ command. This is
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typically useful when parallel make is enabled in the configuration
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(using +BR2_JLEVEL+) but that this feature should be disabled for
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the given package, for one reason or another. By default, set to
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+$(MAKE)+. If parallel building is not supported by the package,
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then it should be set to +LIBFOO_MAKE=$(MAKE1)+.
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* +LIBFOO_MAKE_ENV+, to specify additional environment variables to
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pass to make in the build step. These are passed before the +make+
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command. By default, empty.
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* +LIBFOO_MAKE_OPTS+, to specify additional variables to pass to make
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in the build step. These are passed after the +make+ command. By
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default, empty.
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* +LIBFOO_INSTALL_STAGING_OPTS+ contains the make options used to
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install the package to the staging directory. By default, the value
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is +DESTDIR=$(STAGING_DIR) install+, which is correct for most
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CMake packages. It is still possible to override it.
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* +LIBFOO_INSTALL_TARGET_OPTS+ contains the make options used to
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install the package to the target directory. By default, the value
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is +DESTDIR=$(TARGET_DIR) install+. The default value is correct
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for most CMake packages, but it is still possible to override it if
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needed.
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With the CMake infrastructure, all the steps required to build and
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install the packages are already defined, and they generally work well
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for most CMake-based packages. However, when required, it is still
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possible to customize what is done in any particular step:
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* By adding a post-operation hook (after extract, patch, configure,
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build or install). See xref:hooks[] for details.
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* By overriding one of the steps. For example, even if the CMake
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infrastructure is used, if the package +.mk+ file defines its own
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+LIBFOO_CONFIGURE_CMDS+ variable, it will be used instead of the
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default CMake one. However, using this method should be restricted
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to very specific cases. Do not use it in the general case.
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