- add some anchors to the sample makefile to make ease navigation

   afterwards.</p>

<pre>

     1  #############################################################

     2  #

     3  # foo

     4  #

     5  #############################################################

     6  FOO_VERSION:=1.0

     7  FOO_SOURCE:=foo-$(FOO_VERSION).tar.gz

     8  FOO_SITE:=http://www.foosoftware.org/downloads

     9  FOO_DIR:=$(BUILD_DIR)/foo-$(FOO_VERSION)

    10  FOO_BINARY:=foo

    11  FOO_TARGET_BINARY:=usr/bin/foo

    12

    13  $(DL_DIR)/$(FOO_SOURCE):

    14          $(WGET) -P $(DL_DIR) $(FOO_SITE)/$(FOO_SOURCE)

    15

    16  $(FOO_DIR)/.source: $(DL_DIR)/$(FOO_SOURCE)

    17          $(ZCAT) $(DL_DIR)/$(FOO_SOURCE) | tar -C $(BUILD_DIR) $(TAR_OPTIONS) -

    18          touch $@

    19

    20  $(FOO_DIR)/.configured: $(FOO_DIR)/.source

    21          (cd $(FOO_DIR); rm -rf config.cache ; \

    22                  $(TARGET_CONFIGURE_OPTS) \

    23                  CFLAGS="$(TARGET_CFLAGS)" \

    24                  ./configure \

    25                  --target=$(GNU_TARGET_NAME) \

    26                  --host=$(GNU_TARGET_NAME) \

    27                  --build=$(GNU_HOST_NAME) \

    28                  --prefix=/usr \

    29                  --sysconfdir=/etc \

    30          );

    31          touch $@

    32

    33  $(FOO_DIR)/$(FOO_BINARY): $(FOO_DIR)/.configured

    34          $(MAKE) CC=$(TARGET_CC) -C $(FOO_DIR)

    35

    36  $(TARGET_DIR)/$(FOO_TARGET_BINARY): $(FOO_DIR)/$(FOO_BINARY)

    37          $(MAKE) prefix=$(TARGET_DIR)/usr -C $(FOO_DIR) install

    38          rm -Rf $(TARGET_DIR)/usr/man

    39

    40  foo: uclibc ncurses $(TARGET_DIR)/$(FOO_TARGET_BINARY)

    41

    42  foo-source: $(DL_DIR)/$(FOO_SOURCE)

    43

    44  foo-clean:

    45          $(MAKE) prefix=$(TARGET_DIR)/usr -C $(FOO_DIR) uninstall

    46          -$(MAKE) -C $(FOO_DIR) clean

    47

    48  foo-dirclean:

    49          rm -rf $(FOO_DIR)

    50

    51 #############################################################

    52 #

    53 # Toplevel Makefile options

    54 #

    55 #############################################################

    56 ifeq ($(strip $(BR2_PACKAGE_FOO)),y)

    57 TARGETS+=foo

    58 endif

     <a name="line1" id="line1">1</a>  #############################################################

     <a name="line2" id="line2">2</a>  #

     <a name="line3" id="line3">3</a>  # foo

     <a name="line4" id="line4">4</a>  #

     <a name="line5" id="line5">5</a>  #############################################################

     <a name="line6" id="line6">6</a>  FOO_VERSION:=1.0

     <a name="line7" id="line7">7</a>  FOO_SOURCE:=foo-$(FOO_VERSION).tar.gz

     <a name="line8" id="line8">8</a>  FOO_SITE:=http://www.foosoftware.org/downloads

     <a name="line9" id="line9">9</a>  FOO_DIR:=$(BUILD_DIR)/foo-$(FOO_VERSION)

    <a name="line10" id="line10">10</a>  FOO_BINARY:=foo

    <a name="line11" id="line11">11</a>  FOO_TARGET_BINARY:=usr/bin/foo

    <a name="line12" id="line12">12</a>

    <a name="line13" id="line13">13</a>  $(DL_DIR)/$(FOO_SOURCE):

    <a name="line14" id="line14">14</a>          $(WGET) -P $(DL_DIR) $(FOO_SITE)/$(FOO_SOURCE)

    <a name="line15" id="line15">15</a>

    <a name="line16" id="line16">16</a>  $(FOO_DIR)/.source: $(DL_DIR)/$(FOO_SOURCE)

    <a name="line17" id="line17">17</a>          $(ZCAT) $(DL_DIR)/$(FOO_SOURCE) | tar -C $(BUILD_DIR) $(TAR_OPTIONS) -

    <a name="line18" id="line18">18</a>          touch $@

    <a name="line19" id="line19">19</a>

    <a name="line20" id="line20">20</a>  $(FOO_DIR)/.configured: $(FOO_DIR)/.source

    <a name="line21" id="line21">21</a>          (cd $(FOO_DIR); rm -rf config.cache ; \

    <a name="line22" id="line22">22</a>                  $(TARGET_CONFIGURE_OPTS) \

    <a name="line23" id="line23">23</a>                  CFLAGS="$(TARGET_CFLAGS)" \

    <a name="line24" id="line24">24</a>                  ./configure \

    <a name="line25" id="line25">25</a>                  --target=$(GNU_TARGET_NAME) \

    <a name="line26" id="line26">26</a>                  --host=$(GNU_TARGET_NAME) \

    <a name="line27" id="line27">27</a>                  --build=$(GNU_HOST_NAME) \

    <a name="line28" id="line28">28</a>                  --prefix=/usr \

    <a name="line29" id="line29">29</a>                  --sysconfdir=/etc \

    <a name="line30" id="line30">30</a>          );

    <a name="line31" id="line31">31</a>          touch $@

    <a name="line32" id="line32">32</a>

    <a name="line33" id="line33">33</a>  $(FOO_DIR)/$(FOO_BINARY): $(FOO_DIR)/.configured

    <a name="line34" id="line34">34</a>          $(MAKE) CC=$(TARGET_CC) -C $(FOO_DIR)

    <a name="line35" id="line35">35</a>

    <a name="line36" id="line36">36</a>  $(TARGET_DIR)/$(FOO_TARGET_BINARY): $(FOO_DIR)/$(FOO_BINARY)

    <a name="line37" id="line37">37</a>          $(MAKE) prefix=$(TARGET_DIR)/usr -C $(FOO_DIR) install

    <a name="line38" id="line38">38</a>          rm -Rf $(TARGET_DIR)/usr/man

    <a name="line39" id="line39">39</a>

    <a name="line40" id="line40">40</a>  foo: uclibc ncurses $(TARGET_DIR)/$(FOO_TARGET_BINARY)

    <a name="line41" id="line41">41</a>

    <a name="line42" id="line42">42</a>  foo-source: $(DL_DIR)/$(FOO_SOURCE)

    <a name="line43" id="line43">43</a>

    <a name="line44" id="line44">44</a>  foo-clean:

    <a name="line45" id="line45">45</a>          $(MAKE) prefix=$(TARGET_DIR)/usr -C $(FOO_DIR) uninstall

    <a name="line46" id="line46">46</a>          -$(MAKE) -C $(FOO_DIR) clean

    <a name="line47" id="line47">47</a>

    <a name="line48" id="line48">48</a>  foo-dirclean:

    <a name="line49" id="line49">49</a>          rm -rf $(FOO_DIR)

    <a name="line50" id="line50">50</a>

    <a name="line51" id="line51">51</a> #############################################################

    <a name="line52" id="line52">52</a> #

    <a name="line53" id="line53">53</a> # Toplevel Makefile options

    <a name="line54" id="line54">54</a> #

    <a name="line55" id="line55">55</a> #############################################################

    <a name="line56" id="line56">56</a> ifeq ($(strip $(BR2_PACKAGE_FOO)),y)

    <a name="line57" id="line57">57</a> TARGETS+=foo

    <a name="line58" id="line58">58</a> endif

</pre>

    the other <code>*.mk</code> files in the <code>package</code>

    directory.</p>

    <p>At lines 6-11, a couple of useful variables are defined :</p>

    <p>At lines <a href="#line6">6-11</a>, a couple of useful variables are defined :</p>

    <ul>

    </ul>

    <p>Lines 13-14 defines a target that downloads the tarball from

    <p>Lines <a href="#line13">13-14</a> defines a target that downloads the tarball from

    the remote site to the download directory

    (<code>DL_DIR</code>).</p>

    <p>Lines 16-18 defines a target and associated rules that

    <p>Lines <a href="#line16">16-18</a> defines a target and associated rules that

    uncompress the downloaded tarball. As you can see, this target

    depends on the tarball file, so that the previous target (line

    13-14) is called before executing the rules of the current

    <a href="#line13">13-14</a>) is called before executing the rules of the current

    target. Uncompressing is followed by <i>touching</i> a hidden file

    to mark the software has having been uncompressed. This trick is

    used everywhere in Buildroot <i>Makefile</i> to split steps

    (download, uncompress, configure, compile, install) while still

    having correct dependencies.</p>

    <p>Lines 20-31 defines a target and associated rules that

    <p>Lines <a href="#line20">20-31</a> defines a target and associated rules that

    configures the software. It depends on the previous target (the

    hidden <code>.source</code> file) so that we are sure the software has

    been uncompressed. In order to configure it, it basically runs the

    filesystem. Finally it creates a <code>.configured</code> file to

    mark the software as configured.</p>

    <p>Lines 33-34 defines a target and a rule that compiles the

    <p>Lines <a href="#line33">33-34</a> defines a target and a rule that compiles the

    software. This target will create the binary file in the

    compilation directory, and depends on the software being already

    configured (hence the reference to the <code>.configured</code>

    file). It basically runs <code>make</code> inside the source

    directory.</p>

    <p>Lines 36-38 defines a target and associated rules that install

    <p>Lines <a href="#line36">36-38</a> defines a target and associated rules that install

    the software inside the target filesystem. It depends on the

    binary file in the source directory, to make sure the software has

    been compiled. It uses the <code>install</code> target of the

    <code>/usr/man</code> directory inside the target filesystem is

    removed to save space.</p>

    <p>Line 40 defines the main target of the software, the one

    <p>Line <a href="#line40">40</a> defines the main target of the software, the one

    that will be eventually be used by the top level

    <code>Makefile</code> to download, compile, and then install

    this package. This target should first of all depends on all

    final binary. This last dependency will call all previous

    dependencies in the correct order. </p>

    <p>Line 42 defines a simple target that only downloads the code

    <p>Line <a href="#line42">42</a> defines a simple target that only downloads the code

    source. This is not used during normal operation of Buildroot, but

    is needed if you intend to download all required sources at once

    for later offline build. Note that if you add a new package providing

    users that wish to do offline-builds. Furthermore it eases checking

    if all package-sources are downloadable.</p>

    <p>Lines 44-46 define a simple target to clean the software build

    <p>Lines <a href="#line44">44-46</a> define a simple target to clean the software build

    by calling the <i>Makefiles</i> with the appropriate option.<br>

    The <code>clean</code> target should run <code>make clean</code>

    on $(BUILD_DIR)/package-version and MUST uninstall all files of the

    package from $(STAGING_DIR) and from $(TARGET_DIR).</p>

    <p>Lines 48-49 define a simple target to completely remove the

    <p>Lines <a href="#line48">48-49</a> define a simple target to completely remove the

    directory in which the software was uncompressed, configured and

    compiled. This target MUST completely rm $(BUILD_DIR)/package-version.</p>

    <p>Lines 51-58 adds the target <code>foo</code> to the list

    <p>Lines <a href="#line51">51-58</a> adds the target <code>foo</code> to the list

    of targets to be compiled by Buildroot by first checking if

    the configuration option for this package has been enabled

    using the configuration tool, and if so then "subscribes"

    this package to be compiled by adding it to the TARGETS

    global variable.  The name added to the TARGETS global

    variable is the name of this package's target, as defined on

    line 40, which is used by Buildroot to download, compile, and

    line <a href="#line40">40</a>, which is used by Buildroot to download, compile, and

    then install this package.</p>