2 // vim: set syntax=asciidoc:
4 === Infrastructure for packages with specific build systems
6 By 'packages with specific build systems' we mean all the packages
7 whose build system is not one of the standard ones, such as
8 'autotools' or 'CMake'. This typically includes packages whose build
9 system is based on hand-written Makefiles or shell scripts.
11 [[generic-package-tutorial]]
13 ==== +generic-package+ tutorial
15 ------------------------------
16 01: ################################################################################
20 05: ################################################################################
22 07: LIBFOO_VERSION = 1.0
23 08: LIBFOO_SOURCE = libfoo-$(LIBFOO_VERSION).tar.gz
24 09: LIBFOO_SITE = http://www.foosoftware.org/download
25 10: LIBFOO_LICENSE = GPL-3.0+
26 11: LIBFOO_LICENSE_FILES = COPYING
27 12: LIBFOO_INSTALL_STAGING = YES
28 13: LIBFOO_CONFIG_SCRIPTS = libfoo-config
29 14: LIBFOO_DEPENDENCIES = host-libaaa libbbb
31 16: define LIBFOO_BUILD_CMDS
32 17: $(MAKE) $(TARGET_CONFIGURE_OPTS) -C $(@D) all
35 20: define LIBFOO_INSTALL_STAGING_CMDS
36 21: $(INSTALL) -D -m 0755 $(@D)/libfoo.a $(STAGING_DIR)/usr/lib/libfoo.a
37 22: $(INSTALL) -D -m 0644 $(@D)/foo.h $(STAGING_DIR)/usr/include/foo.h
38 23: $(INSTALL) -D -m 0755 $(@D)/libfoo.so* $(STAGING_DIR)/usr/lib
41 26: define LIBFOO_INSTALL_TARGET_CMDS
42 27: $(INSTALL) -D -m 0755 $(@D)/libfoo.so* $(TARGET_DIR)/usr/lib
43 28: $(INSTALL) -d -m 0755 $(TARGET_DIR)/etc/foo.d
46 31: define LIBFOO_USERS
47 32: foo -1 libfoo -1 * - - - LibFoo daemon
50 35: define LIBFOO_DEVICES
51 36: /dev/foo c 666 0 0 42 0 - - -
54 39: define LIBFOO_PERMISSIONS
55 40: /bin/foo f 4755 foo libfoo - - - - -
58 43: $(eval $(generic-package))
59 --------------------------------
61 The Makefile begins on line 7 to 11 with metadata information: the
62 version of the package (+LIBFOO_VERSION+), the name of the
63 tarball containing the package (+LIBFOO_SOURCE+) (xz-ed tarball recommended)
64 the Internet location at which the tarball can be downloaded from
65 (+LIBFOO_SITE+), the license (+LIBFOO_LICENSE+) and file with the
66 license text (+LIBFOO_LICENSE_FILES+). All variables must start with
67 the same prefix, +LIBFOO_+ in this case. This prefix is always the
68 uppercased version of the package name (see below to understand where
69 the package name is defined).
71 On line 12, we specify that this package wants to install something to
72 the staging space. This is often needed for libraries, since they must
73 install header files and other development files in the staging space.
74 This will ensure that the commands listed in the
75 +LIBFOO_INSTALL_STAGING_CMDS+ variable will be executed.
77 On line 13, we specify that there is some fixing to be done to some
78 of the 'libfoo-config' files that were installed during
79 +LIBFOO_INSTALL_STAGING_CMDS+ phase.
80 These *-config files are executable shell script files that are
81 located in '$(STAGING_DIR)/usr/bin' directory and are executed
82 by other 3rd party packages to find out the location and the linking
83 flags of this particular package.
85 The problem is that all these *-config files by default give wrong,
86 host system linking flags that are unsuitable for cross-compiling.
88 For example: '-I/usr/include' instead of '-I$(STAGING_DIR)/usr/include'
89 or: '-L/usr/lib' instead of '-L$(STAGING_DIR)/usr/lib'
91 So some sed magic is done to these scripts to make them give correct
93 The argument to be given to +LIBFOO_CONFIG_SCRIPTS+ is the file name(s)
94 of the shell script(s) needing fixing. All these names are relative to
95 '$(STAGING_DIR)/usr/bin' and if needed multiple names can be given.
97 In addition, the scripts listed in +LIBFOO_CONFIG_SCRIPTS+ are removed
98 from +$(TARGET_DIR)/usr/bin+, since they are not needed on the target.
100 .Config script: 'divine' package
101 ================================
102 Package divine installs shell script '$(STAGING_DIR)/usr/bin/divine-config'.
104 So its fixup would be:
106 --------------------------------
107 DIVINE_CONFIG_SCRIPTS = divine-config
108 --------------------------------
109 ================================
111 .Config script: 'imagemagick' package:
112 ================================
113 Package imagemagick installs the following scripts:
114 '$(STAGING_DIR)/usr/bin/{Magick,Magick++,MagickCore,MagickWand,Wand}-config'
116 So it's fixup would be:
118 --------------------------------
119 IMAGEMAGICK_CONFIG_SCRIPTS = \
120 Magick-config Magick++-config \
121 MagickCore-config MagickWand-config Wand-config
122 --------------------------------
123 ================================
125 On line 14, we specify the list of dependencies this package relies
126 on. These dependencies are listed in terms of lower-case package names,
127 which can be packages for the target (without the +host-+
128 prefix) or packages for the host (with the +host-+) prefix).
129 Buildroot will ensure that all these packages are built and installed
130 'before' the current package starts its configuration.
132 The rest of the Makefile, lines 16..29, defines what should be done
133 at the different steps of the package configuration, compilation and
135 +LIBFOO_BUILD_CMDS+ tells what steps should be performed to
136 build the package. +LIBFOO_INSTALL_STAGING_CMDS+ tells what
137 steps should be performed to install the package in the staging space.
138 +LIBFOO_INSTALL_TARGET_CMDS+ tells what steps should be
139 performed to install the package in the target space.
141 All these steps rely on the +$(@D)+ variable, which
142 contains the directory where the source code of the package has been
145 On lines 31..43, we define a user that is used by this package (e.g.
146 to run a daemon as non-root) (+LIBFOO_USERS+).
148 On line 35..37, we define a device-node file used by this package
151 On line 39..41, we define the permissions to set to specific files
152 installed by this package (+LIBFOO_PERMISSIONS+).
154 Finally, on line 43, we call the +generic-package+ function, which
155 generates, according to the variables defined previously, all the
156 Makefile code necessary to make your package working.
158 [[generic-package-reference]]
160 ==== +generic-package+ reference
162 There are two variants of the generic target. The +generic-package+ macro is
163 used for packages to be cross-compiled for the target. The
164 +host-generic-package+ macro is used for host packages, natively compiled
165 for the host. It is possible to call both of them in a single +.mk+
166 file: once to create the rules to generate a target
167 package and once to create the rules to generate a host package:
169 ----------------------
170 $(eval $(generic-package))
171 $(eval $(host-generic-package))
172 ----------------------
174 This might be useful if the compilation of the target package requires
175 some tools to be installed on the host. If the package name is
176 +libfoo+, then the name of the package for the target is also
177 +libfoo+, while the name of the package for the host is
178 +host-libfoo+. These names should be used in the DEPENDENCIES
179 variables of other packages, if they depend on +libfoo+ or
182 The call to the +generic-package+ and/or +host-generic-package+ macro *must* be
183 at the end of the +.mk+ file, after all variable definitions.
185 For the target package, the +generic-package+ uses the variables defined by
186 the .mk file and prefixed by the uppercased package name:
187 +LIBFOO_*+. +host-generic-package+ uses the +HOST_LIBFOO_*+ variables. For
188 'some' variables, if the +HOST_LIBFOO_+ prefixed variable doesn't
189 exist, the package infrastructure uses the corresponding variable
190 prefixed by +LIBFOO_+. This is done for variables that are likely to
191 have the same value for both the target and host packages. See below
194 The list of variables that can be set in a +.mk+ file to give metadata
195 information is (assuming the package name is +libfoo+) :
197 * +LIBFOO_VERSION+, mandatory, must contain the version of the
198 package. Note that if +HOST_LIBFOO_VERSION+ doesn't exist, it is
199 assumed to be the same as +LIBFOO_VERSION+. It can also be a
200 revision number, branch or tag for packages that are fetched
201 directly from their revision control system. +
203 +LIBFOO_VERSION = 0.1.2+ +
204 +LIBFOO_VERSION = cb9d6aa9429e838f0e54faa3d455bcbab5eef057+ +
205 +LIBFOO_VERSION = stable+
207 * +LIBFOO_SOURCE+ may contain the name of the tarball of the package,
208 which Buildroot will use to download the tarball from
209 +LIBFOO_SITE+. If +HOST_LIBFOO_SOURCE+ is not specified, it defaults
210 to +LIBFOO_SOURCE+. If none are specified, then the value is assumed
211 to be +libfoo-$(LIBFOO_VERSION).tar.gz+. +
212 Example: +LIBFOO_SOURCE = foobar-$(LIBFOO_VERSION).tar.bz2+
214 * +LIBFOO_PATCH+ may contain a space-separated list of patch file
215 names, that Buildroot will download and apply to the package source
216 code. If an entry contains +://+, then Buildroot will assume it is a
217 full URL and download the patch from this location. Otherwise,
218 Buildroot will assume that the patch should be downloaded from
219 +LIBFOO_SITE+. If +HOST_LIBFOO_PATCH+ is not specified, it defaults
220 to +LIBFOO_PATCH+. Note that patches that are included in Buildroot
221 itself use a different mechanism: all files of the form
222 +*.patch+ present in the package directory inside
223 Buildroot will be applied to the package after extraction (see
224 xref:patch-policy[patching a package]). Finally, patches listed in
225 the +LIBFOO_PATCH+ variable are applied _before_ the patches stored
226 in the Buildroot package directory.
228 * +LIBFOO_SITE+ provides the location of the package, which can be a
229 URL or a local filesystem path. HTTP, FTP and SCP are supported URL
230 types for retrieving package tarballs. In these cases don't include a
231 trailing slash: it will be added by Buildroot between the directory
232 and the filename as appropriate. Git, Subversion, Mercurial,
233 and Bazaar are supported URL types for retrieving packages directly
234 from source code management systems. There is a helper function to make
235 it easier to download source tarballs from GitHub (refer to
236 xref:github-download-url[] for details). A filesystem path may be used
237 to specify either a tarball or a directory containing the package
238 source code. See +LIBFOO_SITE_METHOD+ below for more details on how
240 Note that SCP URLs should be of the form
241 +scp://[user@]host:filepath+, and that filepath is relative to the
242 user's home directory, so you may want to prepend the path with a
243 slash for absolute paths:
244 +scp://[user@]host:/absolutepath+. +
245 If +HOST_LIBFOO_SITE+ is not specified, it defaults to
248 +LIBFOO_SITE=http://www.libfoosoftware.org/libfoo+ +
249 +LIBFOO_SITE=http://svn.xiph.org/trunk/Tremor+ +
250 +LIBFOO_SITE=/opt/software/libfoo.tar.gz+ +
251 +LIBFOO_SITE=$(TOPDIR)/../src/libfoo+
253 * +LIBFOO_DL_OPTS+ is a space-separated list of additional options to
254 pass to the downloader. Useful for retrieving documents with
255 server-side checking for user logins and passwords, or to use a proxy.
256 All download methods valid for +LIBFOO_SITE_METHOD+ are supported;
257 valid options depend on the download method (consult the man page
258 for the respective download utilities).
260 * +LIBFOO_EXTRA_DOWNLOADS+ is a space-separated list of additional
261 files that Buildroot should download. If an entry contains +://+
262 then Buildroot will assume it is a complete URL and will download
263 the file using this URL. Otherwise, Buildroot will assume the file
264 to be downloaded is located at +LIBFOO_SITE+. Buildroot will not do
265 anything with those additional files, except download them: it will
266 be up to the package recipe to use them from +$(DL_DIR)+.
268 * +LIBFOO_SITE_METHOD+ determines the method used to fetch or copy the
269 package source code. In many cases, Buildroot guesses the method
270 from the contents of +LIBFOO_SITE+ and setting +LIBFOO_SITE_METHOD+
271 is unnecessary. When +HOST_LIBFOO_SITE_METHOD+ is not specified, it
272 defaults to the value of +LIBFOO_SITE_METHOD+. +
273 The possible values of +LIBFOO_SITE_METHOD+ are:
274 ** +wget+ for normal FTP/HTTP downloads of tarballs. Used by
275 default when +LIBFOO_SITE+ begins with +http://+, +https://+ or
277 ** +scp+ for downloads of tarballs over SSH with scp. Used by
278 default when +LIBFOO_SITE+ begins with +scp://+.
279 ** +svn+ for retrieving source code from a Subversion repository.
280 Used by default when +LIBFOO_SITE+ begins with +svn://+. When a
281 +http://+ Subversion repository URL is specified in
282 +LIBFOO_SITE+, one 'must' specify +LIBFOO_SITE_METHOD=svn+.
283 Buildroot performs a checkout which is preserved as a tarball in
284 the download cache; subsequent builds use the tarball instead of
285 performing another checkout.
286 ** +cvs+ for retrieving source code from a CVS repository.
287 Used by default when +LIBFOO_SITE+ begins with +cvs://+.
288 The downloaded source code is cached as with the +svn+ method.
289 Anonymous pserver mode is assumed otherwise explicitly defined
290 on +LIBFOO_SITE+. Both
291 +LIBFOO_SITE=cvs://libfoo.net:/cvsroot/libfoo+ and
292 +LIBFOO_SITE=cvs://:ext:libfoo.net:/cvsroot/libfoo+
293 are accepted, on the former anonymous pserver access mode is
295 +LIBFOO_SITE+ 'must' contain the source URL as well as the remote
296 repository directory. The module is the package name.
297 +LIBFOO_VERSION+ is 'mandatory' and 'must' be a tag, a branch, or
298 a date (e.g. "2014-10-20", "2014-10-20 13:45", "2014-10-20
299 13:45+01" see "man cvs" for further details).
300 ** +git+ for retrieving source code from a Git repository. Used by
301 default when +LIBFOO_SITE+ begins with +git://+. The downloaded
302 source code is cached as with the +svn+
304 ** +hg+ for retrieving source code from a Mercurial repository. One
305 'must' specify +LIBFOO_SITE_METHOD=hg+ when +LIBFOO_SITE+
306 contains a Mercurial repository URL. The downloaded source code
307 is cached as with the +svn+ method.
308 ** +bzr+ for retrieving source code from a Bazaar repository. Used
309 by default when +LIBFOO_SITE+ begins with +bzr://+. The
310 downloaded source code is cached as with the +svn+ method.
311 ** +file+ for a local tarball. One should use this when
312 +LIBFOO_SITE+ specifies a package tarball as a local filename.
313 Useful for software that isn't available publicly or in version
315 ** +local+ for a local source code directory. One should use this
316 when +LIBFOO_SITE+ specifies a local directory path containing
317 the package source code. Buildroot copies the contents of the
318 source directory into the package's build directory. Note that
319 for +local+ packages, no patches are applied. If you need to
320 still patch the source code, use +LIBFOO_POST_RSYNC_HOOKS+, see
323 * +LIBFOO_GIT_SUBMODULES+ can be set to +YES+ to create an archive
324 with the git submodules in the repository. This is only available
325 for packages downloaded with git (i.e. when
326 +LIBFOO_SITE_METHOD=git+). Note that we try not to use such git
327 submodules when they contain bundled libraries, in which case we
328 prefer to use those libraries from their own package.
330 * +LIBFOO_STRIP_COMPONENTS+ is the number of leading components
331 (directories) that tar must strip from file names on extraction.
332 The tarball for most packages has one leading component named
333 "<pkg-name>-<pkg-version>", thus Buildroot passes
334 --strip-components=1 to tar to remove it.
335 For non-standard packages that don't have this component, or
336 that have more than one leading component to strip, set this
337 variable with the value to be passed to tar. Default: 1.
339 * +LIBFOO_EXCLUDES+ is a space-separated list of patterns to exclude
340 when extracting the archive. Each item from that list is passed as
341 a tar's +--exclude+ option. By default, empty.
343 * +LIBFOO_DEPENDENCIES+ lists the dependencies (in terms of package
344 name) that are required for the current target package to
345 compile. These dependencies are guaranteed to be compiled and
346 installed before the configuration of the current package starts. In
347 a similar way, +HOST_LIBFOO_DEPENDENCIES+ lists the dependencies for
348 the current host package.
350 * +LIBFOO_PATCH_DEPENDENCIES+ lists the dependencies (in terms of
351 package name) that are required for the current package to be
352 patched. These dependencies are guaranteed to be extracted and
353 patched before the current package is patched. In a similar way,
354 +HOST_LIBFOO_PATCH_DEPENDENCIES+ lists the dependencies for the
355 current host package.
356 This is seldom used; usually, +LIBFOO_DEPENDENCIES+ is what you
359 * +LIBFOO_PROVIDES+ lists all the virtual packages +libfoo+ is an
360 implementation of. See xref:virtual-package-tutorial[].
362 * +LIBFOO_INSTALL_STAGING+ can be set to +YES+ or +NO+ (default). If
363 set to +YES+, then the commands in the +LIBFOO_INSTALL_STAGING_CMDS+
364 variables are executed to install the package into the staging
367 * +LIBFOO_INSTALL_TARGET+ can be set to +YES+ (default) or +NO+. If
368 set to +YES+, then the commands in the +LIBFOO_INSTALL_TARGET_CMDS+
369 variables are executed to install the package into the target
372 * +LIBFOO_INSTALL_IMAGES+ can be set to +YES+ or +NO+ (default). If
373 set to +YES+, then the commands in the +LIBFOO_INSTALL_IMAGES_CMDS+
374 variable are executed to install the package into the images
377 * +LIBFOO_CONFIG_SCRIPTS+ lists the names of the files in
378 '$(STAGING_DIR)/usr/bin' that need some special fixing to make them
379 cross-compiling friendly. Multiple file names separated by space can
380 be given and all are relative to '$(STAGING_DIR)/usr/bin'. The files
381 listed in +LIBFOO_CONFIG_SCRIPTS+ are also removed from
382 +$(TARGET_DIR)/usr/bin+ since they are not needed on the target.
384 * +LIBFOO_DEVICES+ lists the device files to be created by Buildroot
385 when using the static device table. The syntax to use is the
386 makedevs one. You can find some documentation for this syntax in the
387 xref:makedev-syntax[]. This variable is optional.
389 * +LIBFOO_PERMISSIONS+ lists the changes of permissions to be done at
390 the end of the build process. The syntax is once again the makedevs one.
391 You can find some documentation for this syntax in the xref:makedev-syntax[].
392 This variable is optional.
394 * +LIBFOO_USERS+ lists the users to create for this package, if it installs
395 a program you want to run as a specific user (e.g. as a daemon, or as a
396 cron-job). The syntax is similar in spirit to the makedevs one, and is
397 described in the xref:makeuser-syntax[]. This variable is optional.
399 * +LIBFOO_LICENSE+ defines the license (or licenses) under which the package
401 This name will appear in the manifest file produced by +make legal-info+.
402 If the license appears in https://spdx.org/licenses/[the SPDX License List],
403 use the SPDX short identifier to make the manifest file uniform.
404 Otherwise, describe the license in a precise and concise way, avoiding
405 ambiguous names such as +BSD+ which actually name a family of licenses.
406 This variable is optional. If it is not defined, +unknown+ will appear in
407 the +license+ field of the manifest file for this package. +
408 The expected format for this variable must comply with the following rules:
409 ** If different parts of the package are released under different
410 licenses, then +comma+ separate licenses (e.g. +`LIBFOO_LICENSE =
411 GPL-2.0+, LGPL-2.1+`+). If there is clear distinction between which
412 component is licensed under what license, then annotate the license
413 with that component, between parenthesis (e.g. +`LIBFOO_LICENSE =
414 GPL-2.0+ (programs), LGPL-2.1+ (libraries)`+).
415 ** If the package is dual licensed, then separate licenses with the
416 +or+ keyword (e.g. +`LIBFOO_LICENSE = AFL-2.1 or GPL-2.0+`+).
418 * +LIBFOO_LICENSE_FILES+ is a space-separated list of files in the package
419 tarball that contain the license(s) under which the package is released.
420 +make legal-info+ copies all of these files in the +legal-info+ directory.
421 See xref:legal-info[] for more information.
422 This variable is optional. If it is not defined, a warning will be produced
423 to let you know, and +not saved+ will appear in the +license files+ field
424 of the manifest file for this package.
426 * +LIBFOO_ACTUAL_SOURCE_TARBALL+ only applies to packages whose
427 +LIBFOO_SITE+ / +LIBTOO_SOURCE+ pair points to an archive that does
428 not actually contain source code, but binary code. This a very
429 uncommon case, only known to apply to external toolchains which come
430 already compiled, although theoretically it might apply to other
431 packages. In such cases a separate tarball is usually available with
432 the actual source code. Set +LIBFOO_ACTUAL_SOURCE_TARBALL+ to the
433 name of the actual source code archive and Buildroot will download
434 it and use it when you run +make legal-info+ to collect
435 legally-relevant material. Note this file will not be downloaded
436 during regular builds nor by +make source+.
438 * +LIBFOO_ACTUAL_SOURCE_SITE+ provides the location of the actual
439 source tarball. The default value is +LIBFOO_SITE+, so you don't
440 need to set this variable if the binary and source archives are
441 hosted on the same directory. If +LIBFOO_ACTUAL_SOURCE_TARBALL+ is
442 not set, it doesn't make sense to define
443 +LIBFOO_ACTUAL_SOURCE_SITE+.
445 * +LIBFOO_REDISTRIBUTE+ can be set to +YES+ (default) or +NO+ to indicate if
446 the package source code is allowed to be redistributed. Set it to +NO+ for
447 non-opensource packages: Buildroot will not save the source code for this
448 package when collecting the +legal-info+.
450 * +LIBFOO_FLAT_STACKSIZE+ defines the stack size of an application built into
451 the FLAT binary format. The application stack size on the NOMMU architecture
452 processors can't be enlarged at run time. The default stack size for the
453 FLAT binary format is only 4k bytes. If the application consumes more stack,
454 append the required number here.
456 * +LIBFOO_BIN_ARCH_EXCLUDE+ is a space-separated list of paths (relative
457 to the target directory) to ignore when checking that the package
458 installs correctly cross-compiled binaries. You seldom need to set this
459 variable, unless the package installs binary blobs outside the default
460 locations, `/lib/firmware`, `/usr/lib/firmware`, `/lib/modules`,
461 `/usr/lib/modules`, and `/usr/share`, which are automatically excluded.
463 The recommended way to define these variables is to use the following
466 ----------------------
467 LIBFOO_VERSION = 2.32
468 ----------------------
470 Now, the variables that define what should be performed at the
471 different steps of the build process.
473 * +LIBFOO_EXTRACT_CMDS+ lists the actions to be performed to extract
474 the package. This is generally not needed as tarballs are
475 automatically handled by Buildroot. However, if the package uses a
476 non-standard archive format, such as a ZIP or RAR file, or has a
477 tarball with a non-standard organization, this variable allows to
478 override the package infrastructure default behavior.
480 * +LIBFOO_CONFIGURE_CMDS+ lists the actions to be performed to
481 configure the package before its compilation.
483 * +LIBFOO_BUILD_CMDS+ lists the actions to be performed to
486 * +HOST_LIBFOO_INSTALL_CMDS+ lists the actions to be performed
487 to install the package, when the package is a host package. The
488 package must install its files to the directory given by
489 +$(HOST_DIR)+. All files, including development files such as
490 headers should be installed, since other packages might be compiled
491 on top of this package.
493 * +LIBFOO_INSTALL_TARGET_CMDS+ lists the actions to be
494 performed to install the package to the target directory, when the
495 package is a target package. The package must install its files to
496 the directory given by +$(TARGET_DIR)+. Only the files required for
497 'execution' of the package have to be
498 installed. Header files, static libraries and documentation will be
499 removed again when the target filesystem is finalized.
501 * +LIBFOO_INSTALL_STAGING_CMDS+ lists the actions to be
502 performed to install the package to the staging directory, when the
503 package is a target package. The package must install its files to
504 the directory given by +$(STAGING_DIR)+. All development files
505 should be installed, since they might be needed to compile other
508 * +LIBFOO_INSTALL_IMAGES_CMDS+ lists the actions to be performed to
509 install the package to the images directory, when the package is a
510 target package. The package must install its files to the directory
511 given by +$(BINARIES_DIR)+. Only files that are binary images (aka
512 images) that do not belong in the +TARGET_DIR+ but are necessary
513 for booting the board should be placed here. For example, a package
514 should utilize this step if it has binaries which would be similar
515 to the kernel image, bootloader or root filesystem images.
517 * +LIBFOO_INSTALL_INIT_SYSV+ and +LIBFOO_INSTALL_INIT_SYSTEMD+ list the
518 actions to install init scripts either for the systemV-like init systems
519 (busybox, sysvinit, etc.) or for the systemd units. These commands
520 will be run only when the relevant init system is installed (i.e. if
521 systemd is selected as the init system in the configuration, only
522 +LIBFOO_INSTALL_INIT_SYSTEMD+ will be run).
524 * +LIBFOO_HELP_CMDS+ lists the actions to print the package help, which
525 is included to the main +make help+ output. These commands can print
526 anything in any format.
527 This is seldom used, as packages rarely have custom rules. *Do not use
528 this variable*, unless you really know that you need to print help.
530 The preferred way to define these variables is:
532 ----------------------
533 define LIBFOO_CONFIGURE_CMDS
538 ----------------------
540 In the action definitions, you can use the following variables:
542 * +$(LIBFOO_PKGDIR)+ contains the path to the directory containing the
543 +libfoo.mk+ and +Config.in+ files. This variable is useful when it is
544 necessary to install a file bundled in Buildroot, like a runtime
545 configuration file, a splashscreen image...
547 * +$(@D)+, which contains the directory in which the package source
548 code has been uncompressed.
550 * +$(DL_DIR)+ contains the path to the directory where all the downloads made
551 by Buildroot are stored.
553 * +$(TARGET_CC)+, +$(TARGET_LD)+, etc. to get the target
554 cross-compilation utilities
556 * +$(TARGET_CROSS)+ to get the cross-compilation toolchain prefix
558 * Of course the +$(HOST_DIR)+, +$(STAGING_DIR)+ and +$(TARGET_DIR)+
559 variables to install the packages properly.
561 Finally, you can also use hooks. See xref:hooks[] for more information.