kumquat-buildroot/docs/manual/adding-packages-cmake.txt

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// -*- mode:doc; -*-
// vim: set syntax=asciidoc:
manual: use one-line titles instead of two-line titles (trivial) Asciidoc supports two syntaxes for section titles: two-line titles (title plus underline consisting of a particular symbol), and one-line titles (title prefixed with a specific number of = signs). The two-line title underlines are: Level 0 (top level): ====================== Level 1: ---------------------- Level 2: ~~~~~~~~~~~~~~~~~~~~~~ Level 3: ^^^^^^^^^^^^^^^^^^^^^^ Level 4 (bottom level): ++++++++++++++++++++++ and the one-line title prefixes: = Document Title (level 0) = == Section title (level 1) == === Section title (level 2) === ==== Section title (level 3) ==== ===== Section title (level 4) ===== The buildroot manual is currenly using the two-line titles, but this has multiple disadvantages: - asciidoc also uses some of the underline symbols for other purposes (like preformatted code, example blocks, ...), which makes it difficult to do mass replacements, such as a planned follow-up patch that needs to move all sections one level down. - it is difficult to remember which level a given underline symbol (=-~^+) corresponds to, while counting = signs is easy. This patch changes all two-level titles to one-level titles in the manual. The bulk of the change was done with the following Python script, except for the level 1 titles (-----) as these underlines are also used for literal code blocks. This patch only changes the titles, no other changes. In adding-packages-directory.txt, I did add missing newlines between some titles and their content. ---------------------------------------------------------------------------- #!/usr/bin/env python import sys import mmap import re for input in sys.argv[1:]: f = open(input, 'r+') f.flush() s = mmap.mmap(f.fileno(), 0) # Level 0 (top level): ====================== = # Level 1: ---------------------- == # Level 2: ~~~~~~~~~~~~~~~~~~~~~~ === # Level 3: ^^^^^^^^^^^^^^^^^^^^^^ ==== # Level 4 (bottom level): ++++++++++++++++++++++ ===== def replace_title(s, symbol, replacement): pattern = re.compile(r'(.+\n)\%s{2,}\n' % symbol, re.MULTILINE) return pattern.sub(r'%s \1' % replacement, s) new = s new = replace_title(new, '=', '=') new = replace_title(new, '+', '=====') new = replace_title(new, '^', '====') new = replace_title(new, '~', '===') #new = replace_title(new, '-', '==') s.seek(0) s.write(new) s.resize(s.tell()) s.close() f.close() ---------------------------------------------------------------------------- Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
2014-05-02 07:47:30 +02:00
=== Infrastructure for CMake-based packages
[[cmake-package-tutorial]]
manual: use one-line titles instead of two-line titles (trivial) Asciidoc supports two syntaxes for section titles: two-line titles (title plus underline consisting of a particular symbol), and one-line titles (title prefixed with a specific number of = signs). The two-line title underlines are: Level 0 (top level): ====================== Level 1: ---------------------- Level 2: ~~~~~~~~~~~~~~~~~~~~~~ Level 3: ^^^^^^^^^^^^^^^^^^^^^^ Level 4 (bottom level): ++++++++++++++++++++++ and the one-line title prefixes: = Document Title (level 0) = == Section title (level 1) == === Section title (level 2) === ==== Section title (level 3) ==== ===== Section title (level 4) ===== The buildroot manual is currenly using the two-line titles, but this has multiple disadvantages: - asciidoc also uses some of the underline symbols for other purposes (like preformatted code, example blocks, ...), which makes it difficult to do mass replacements, such as a planned follow-up patch that needs to move all sections one level down. - it is difficult to remember which level a given underline symbol (=-~^+) corresponds to, while counting = signs is easy. This patch changes all two-level titles to one-level titles in the manual. The bulk of the change was done with the following Python script, except for the level 1 titles (-----) as these underlines are also used for literal code blocks. This patch only changes the titles, no other changes. In adding-packages-directory.txt, I did add missing newlines between some titles and their content. ---------------------------------------------------------------------------- #!/usr/bin/env python import sys import mmap import re for input in sys.argv[1:]: f = open(input, 'r+') f.flush() s = mmap.mmap(f.fileno(), 0) # Level 0 (top level): ====================== = # Level 1: ---------------------- == # Level 2: ~~~~~~~~~~~~~~~~~~~~~~ === # Level 3: ^^^^^^^^^^^^^^^^^^^^^^ ==== # Level 4 (bottom level): ++++++++++++++++++++++ ===== def replace_title(s, symbol, replacement): pattern = re.compile(r'(.+\n)\%s{2,}\n' % symbol, re.MULTILINE) return pattern.sub(r'%s \1' % replacement, s) new = s new = replace_title(new, '=', '=') new = replace_title(new, '+', '=====') new = replace_title(new, '^', '====') new = replace_title(new, '~', '===') #new = replace_title(new, '-', '==') s.seek(0) s.write(new) s.resize(s.tell()) s.close() f.close() ---------------------------------------------------------------------------- Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
2014-05-02 07:47:30 +02:00
==== +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]]
manual: use one-line titles instead of two-line titles (trivial) Asciidoc supports two syntaxes for section titles: two-line titles (title plus underline consisting of a particular symbol), and one-line titles (title prefixed with a specific number of = signs). The two-line title underlines are: Level 0 (top level): ====================== Level 1: ---------------------- Level 2: ~~~~~~~~~~~~~~~~~~~~~~ Level 3: ^^^^^^^^^^^^^^^^^^^^^^ Level 4 (bottom level): ++++++++++++++++++++++ and the one-line title prefixes: = Document Title (level 0) = == Section title (level 1) == === Section title (level 2) === ==== Section title (level 3) ==== ===== Section title (level 4) ===== The buildroot manual is currenly using the two-line titles, but this has multiple disadvantages: - asciidoc also uses some of the underline symbols for other purposes (like preformatted code, example blocks, ...), which makes it difficult to do mass replacements, such as a planned follow-up patch that needs to move all sections one level down. - it is difficult to remember which level a given underline symbol (=-~^+) corresponds to, while counting = signs is easy. This patch changes all two-level titles to one-level titles in the manual. The bulk of the change was done with the following Python script, except for the level 1 titles (-----) as these underlines are also used for literal code blocks. This patch only changes the titles, no other changes. In adding-packages-directory.txt, I did add missing newlines between some titles and their content. ---------------------------------------------------------------------------- #!/usr/bin/env python import sys import mmap import re for input in sys.argv[1:]: f = open(input, 'r+') f.flush() s = mmap.mmap(f.fileno(), 0) # Level 0 (top level): ====================== = # Level 1: ---------------------- == # Level 2: ~~~~~~~~~~~~~~~~~~~~~~ === # Level 3: ^^^^^^^^^^^^^^^^^^^^^^ ==== # Level 4 (bottom level): ++++++++++++++++++++++ ===== def replace_title(s, symbol, replacement): pattern = re.compile(r'(.+\n)\%s{2,}\n' % symbol, re.MULTILINE) return pattern.sub(r'%s \1' % replacement, s) new = s new = replace_title(new, '=', '=') new = replace_title(new, '+', '=====') new = replace_title(new, '^', '====') new = replace_title(new, '~', '===') #new = replace_title(new, '-', '==') s.seek(0) s.write(new) s.resize(s.tell()) s.close() f.close() ---------------------------------------------------------------------------- Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
2014-05-02 07:47:30 +02:00
==== +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:
package/pkg-cmake.mk: determine CMAKE_BUILD_TYPE depending on BR2_ENABLE_RUNTIME_DEBUG The CMAKE_BUILD_TYPE is currently set as 'Debug' in case BR2_ENABLE_DEBUG is set, and as 'Release' in other cases. However, while the description of BR2_ENABLE_DEBUG is to enable debug symbols (no runtime impact), the 'Debug' build type in CMake can actually have runtime impact. For one, because it does not set -DNDEBUG like is done for 'Release', but also because packages may do custom things based on it. The question of which CMAKE_BUILD_TYPE Buildroot should set, be it 'Debug', 'Release', 'RelWithDebInfo' or others, has come up several times in the past. See some references below: - July 2016: switch from Debug to RelWithDebInfo: https://git.buildroot.org/buildroot/commit/?id=4b0120183404913f7f7788ef4f0f6b51498ef363 - October 2016: switch from RelWithDebInfo back to Debug: https://git.buildroot.org/buildroot/commit/?id=104bb29e0490bfb487e2e665448dd3ca07fcc2b5 and changes to make sure Buildroot's flags are respected: https://git.buildroot.org/buildroot/commit/?id=12494ef48f893684d0800e7f6fe39a2ceaed0451 - August 2017: bug #10246 - "BR2_ENABLE_DEBUG does not have the expected effect for cmake packages" https://bugs.busybox.net/show_bug.cgi?id=10246 - August 2017: mail thread following bug #10246: http://lists.busybox.net/pipermail/buildroot/2017-August/200778.html In the last mail thread, Samuel Martin confirmed that the 'Release' build type could be used in all cases, because Buildroot is actually making sure that the optimization flags are those determined by Buildroot, not the defaults of cmake, thanks to commit 12494ef48f. But Arnout Vandecappelle objected to using always 'Release', stating that users may actually want the extra assertions. With the introduction of BR2_ENABLE_RUNTIME_DEBUG, Buildroot can now cater for all cases: - use CMAKE_BUILD_TYPE=Release by default. This makes sure that there is no unexpected performance degradation triggered by enabling BR2_ENABLE_DEBUG. - users can optionally enable BR2_ENABLE_RUNTIME_DEBUG if they want runtime debug info like assertions, at the risk of introducing performance degradation. In this case, we switch to CMAKE_BUILD_TYPE=Debug. - orthogonally to the above, BR2_ENABLE_DEBUG still determines passing the '-g' flag to enable debug symbols, and BR2_OPTIMIZE_X still determines the used optimization flags. Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com> Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Reviewed-by: Yann E. MORIN <yann.morin.1998@free.fr> Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
2021-06-01 16:34:08 +02:00
** +CMAKE_BUILD_TYPE+ is driven by +BR2_ENABLE_RUNTIME_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=$(MAKE1)+.
* +LIBFOO_MAKE_ENV+, to specify additional environment variables to
pass to make in the build step. These are passed before the +make+
command. By default, empty.
* +LIBFOO_MAKE_OPTS+, to specify additional variables to pass to make
in the build step. These are passed after the +make+ command. By
default, empty.
* +LIBFOO_INSTALL_OPTS+ contains the make options used to
install the package to the host directory. By default, the value
is +install+, which is correct for most CMake packages. It is still
possible to override it.
* +LIBFOO_INSTALL_STAGING_OPTS+ contains the make options used to
install the package to the staging directory. By default, the value
is +DESTDIR=$(STAGING_DIR) install/fast+, 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/fast+. 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.