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authorRichard Purdie <richard.purdie@linuxfoundation.org>2014-01-17 16:22:42 +0000
committerRichard Purdie <richard.purdie@linuxfoundation.org>2014-01-27 21:03:19 +0000
commit633db4f0ff77fdeec0ba88794686083f2fc283dd (patch)
tree8630604f98139d28e9c47d784ccc92587c2e1336 /bitbake/doc
parent437791a23d7b82e23f63956857deb3ed5c4e3a21 (diff)
downloadpoky-633db4f0ff77fdeec0ba88794686083f2fc283dd.tar.gz
bitbake: user-manual-metadata: Add section ids for most sections
(Bitbake rev: 4ad94fb161d5fe24869696187e01004bff61d569) Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'bitbake/doc')
-rw-r--r--bitbake/doc/user-manual/user-manual-metadata.xml92
1 files changed, 59 insertions, 33 deletions
diff --git a/bitbake/doc/user-manual/user-manual-metadata.xml b/bitbake/doc/user-manual/user-manual-metadata.xml
index a9117f8255..10014929b9 100644
--- a/bitbake/doc/user-manual/user-manual-metadata.xml
+++ b/bitbake/doc/user-manual/user-manual-metadata.xml
@@ -1,6 +1,6 @@
1<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" 1<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
2 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> 2 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
3 <chapter> 3 <chapter id="user-manual-metadata">
4 <title>Metadata</title> 4 <title>Metadata</title>
5 <section> 5 <section>
6 <title>Description</title> 6 <title>Description</title>
@@ -17,30 +17,39 @@
17 </listitem> 17 </listitem>
18 </itemizedlist> 18 </itemizedlist>
19 <para>What follows are a large number of examples of BitBake metadata. Any syntax which isn't supported in any of the aforementioned areas will be documented as such.</para> 19 <para>What follows are a large number of examples of BitBake metadata. Any syntax which isn't supported in any of the aforementioned areas will be documented as such.</para>
20 <section> 20 </section>
21
22 <section id='basic-syntax'>
23 <title>Basic Syntax</title>
24
25 <section id='basic-variable-setting'>
21 <title>Basic variable setting</title> 26 <title>Basic variable setting</title>
22 <para><screen><varname>VARIABLE</varname> = "value"</screen></para> 27 <para><screen><varname>VARIABLE</varname> = "value"</screen></para>
23 <para>In this example, <varname>VARIABLE</varname> is <literal>value</literal>.</para> 28 <para>In this example, <varname>VARIABLE</varname> is <literal>value</literal>.</para>
24 </section> 29 </section>
25 <section> 30
31 <section id='variable-expansion'>
26 <title>Variable expansion</title> 32 <title>Variable expansion</title>
27 <para>BitBake supports variables referencing one another's contents using a syntax which is similar to shell scripting</para> 33 <para>BitBake supports variables referencing one another's contents using a syntax which is similar to shell scripting</para>
28 <para><screen><varname>A</varname> = "aval" 34 <para><screen><varname>A</varname> = "aval"
29<varname>B</varname> = "pre${A}post"</screen></para> 35<varname>B</varname> = "pre${A}post"</screen></para>
30 <para>This results in <varname>A</varname> containing <literal>aval</literal> and <varname>B</varname> containing <literal>preavalpost</literal>.</para> 36 <para>This results in <varname>A</varname> containing <literal>aval</literal> and <varname>B</varname> containing <literal>preavalpost</literal>.</para>
31 </section> 37 </section>
32 <section> 38
39 <section id='setting-a-default-value'>
33 <title>Setting a default value (?=)</title> 40 <title>Setting a default value (?=)</title>
34 <para><screen><varname>A</varname> ?= "aval"</screen></para> 41 <para><screen><varname>A</varname> ?= "aval"</screen></para>
35 <para>If <varname>A</varname> is set before the above is called, it will retain its previous value. If <varname>A</varname> is unset prior to the above call, <varname>A</varname> will be set to <literal>aval</literal>. Note that this assignment is immediate, so if there are multiple ?= assignments to a single variable, the first of those will be used.</para> 42 <para>If <varname>A</varname> is set before the above is called, it will retain its previous value. If <varname>A</varname> is unset prior to the above call, <varname>A</varname> will be set to <literal>aval</literal>. Note that this assignment is immediate, so if there are multiple ?= assignments to a single variable, the first of those will be used.</para>
36 </section> 43 </section>
37 <section> 44
45 <section id='setting-a-weak-default-value'>
38 <title>Setting a weak default value (??=)</title> 46 <title>Setting a weak default value (??=)</title>
39 <para><screen><varname>A</varname> ??= "somevalue" 47 <para><screen><varname>A</varname> ??= "somevalue"
40<varname>A</varname> ??= "someothervalue"</screen></para> 48<varname>A</varname> ??= "someothervalue"</screen></para>
41 <para>If <varname>A</varname> is set before the above, it will retain that value. If <varname>A</varname> is unset prior to the above, <varname>A</varname> will be set to <literal>someothervalue</literal>. This is a lazy/weak assignment in that the assignment does not occur until the end of the parsing process, so that the last, rather than the first, ??= assignment to a given variable will be used. Any other setting of A using = or ?= will however override the value set with ??=</para> 49 <para>If <varname>A</varname> is set before the above, it will retain that value. If <varname>A</varname> is unset prior to the above, <varname>A</varname> will be set to <literal>someothervalue</literal>. This is a lazy/weak assignment in that the assignment does not occur until the end of the parsing process, so that the last, rather than the first, ??= assignment to a given variable will be used. Any other setting of A using = or ?= will however override the value set with ??=</para>
42 </section> 50 </section>
43 <section> 51
52 <section id='immediate-variable-expansion'>
44 <title>Immediate variable expansion (:=)</title> 53 <title>Immediate variable expansion (:=)</title>
45 <para>:= results in a variable's contents being expanded immediately, rather than when the variable is actually used.</para> 54 <para>:= results in a variable's contents being expanded immediately, rather than when the variable is actually used.</para>
46 <para><screen><varname>T</varname> = "123" 55 <para><screen><varname>T</varname> = "123"
@@ -52,7 +61,8 @@
52<varname>C</varname> := "${C}append"</screen></para> 61<varname>C</varname> := "${C}append"</screen></para>
53 <para>In that example, <varname>A</varname> would contain <literal> test 123</literal>, <varname>B</varname> would contain <literal>456 bval</literal>, and <varname>C</varname> would be <literal>cvalappend</literal>.</para> 62 <para>In that example, <varname>A</varname> would contain <literal> test 123</literal>, <varname>B</varname> would contain <literal>456 bval</literal>, and <varname>C</varname> would be <literal>cvalappend</literal>.</para>
54 </section> 63 </section>
55 <section> 64
65 <section id='appending-and-prepending'>
56 <title>Appending (+=) and prepending (=+)</title> 66 <title>Appending (+=) and prepending (=+)</title>
57 <para><screen><varname>B</varname> = "bval" 67 <para><screen><varname>B</varname> = "bval"
58<varname>B</varname> += "additionaldata" 68<varname>B</varname> += "additionaldata"
@@ -60,7 +70,8 @@
60<varname>C</varname> =+ "test"</screen></para> 70<varname>C</varname> =+ "test"</screen></para>
61 <para>In this example, <varname>B</varname> is now <literal>bval additionaldata</literal> and <varname>C</varname> is <literal>test cval</literal>.</para> 71 <para>In this example, <varname>B</varname> is now <literal>bval additionaldata</literal> and <varname>C</varname> is <literal>test cval</literal>.</para>
62 </section> 72 </section>
63 <section> 73
74 <section id='appending-and-prepending-without-spaces'>
64 <title>Appending (.=) and prepending (=.) without spaces</title> 75 <title>Appending (.=) and prepending (=.) without spaces</title>
65 <para><screen><varname>B</varname> = "bval" 76 <para><screen><varname>B</varname> = "bval"
66<varname>B</varname> .= "additionaldata" 77<varname>B</varname> .= "additionaldata"
@@ -69,7 +80,8 @@
69 <para>In this example, <varname>B</varname> is now <literal>bvaladditionaldata</literal> and <varname>C</varname> is <literal>testcval</literal>. In contrast to the above appending and prepending operators, no additional space 80 <para>In this example, <varname>B</varname> is now <literal>bvaladditionaldata</literal> and <varname>C</varname> is <literal>testcval</literal>. In contrast to the above appending and prepending operators, no additional space
70will be introduced.</para> 81will be introduced.</para>
71 </section> 82 </section>
72 <section> 83
84 <section id='appending-and-prepending-override-style-syntax'>
73 <title>Appending and Prepending (override style syntax)</title> 85 <title>Appending and Prepending (override style syntax)</title>
74 <para><screen><varname>B</varname> = "bval" 86 <para><screen><varname>B</varname> = "bval"
75<varname>B_append</varname> = " additional data" 87<varname>B_append</varname> = " additional data"
@@ -80,14 +92,16 @@ and <varname>C</varname> becoming <literal>additional data cval</literal>. Note
80Unlike the += operator, additional space is not automatically added. You must take steps to add space 92Unlike the += operator, additional space is not automatically added. You must take steps to add space
81yourself.</para> 93yourself.</para>
82 </section> 94 </section>
83 <section> 95
96 <section id='removing-override-style-syntax'>
84 <title>Removing (override style syntax)</title> 97 <title>Removing (override style syntax)</title>
85 <para><screen><varname>FOO</varname> = "123 456 789 123456 123 456 123 456" 98 <para><screen><varname>FOO</varname> = "123 456 789 123456 123 456 123 456"
86<varname>FOO_remove</varname> = "123" 99<varname>FOO_remove</varname> = "123"
87<varname>FOO_remove</varname> = "456"</screen></para> 100<varname>FOO_remove</varname> = "456"</screen></para>
88 <para>In this example, <varname>FOO</varname> is now <literal>789 123456</literal>.</para> 101 <para>In this example, <varname>FOO</varname> is now <literal>789 123456</literal>.</para>
89 </section> 102 </section>
90 <section> 103
104 <section id='conditional-syntax-overrides'>
91 <title>Conditional metadata set</title> 105 <title>Conditional metadata set</title>
92 <para>OVERRIDES is a <quote>:</quote> separated variable containing each item you want to satisfy conditions. So, if you have a variable which is conditional on <quote>arm</quote>, and <quote>arm</quote> is in OVERRIDES, then the <quote>arm</quote> specific version of the variable is used rather than the non-conditional version. Example:</para> 106 <para>OVERRIDES is a <quote>:</quote> separated variable containing each item you want to satisfy conditions. So, if you have a variable which is conditional on <quote>arm</quote>, and <quote>arm</quote> is in OVERRIDES, then the <quote>arm</quote> specific version of the variable is used rather than the non-conditional version. Example:</para>
93 <para><screen><varname>OVERRIDES</varname> = "architecture:os:machine" 107 <para><screen><varname>OVERRIDES</varname> = "architecture:os:machine"
@@ -96,7 +110,8 @@ yourself.</para>
96<varname>TEST_condnotinoverrides</varname> = "othercondvalue"</screen></para> 110<varname>TEST_condnotinoverrides</varname> = "othercondvalue"</screen></para>
97 <para>In this example, <varname>TEST</varname> would be <literal>osspecificvalue</literal>, due to the condition <quote>os</quote> being in <varname>OVERRIDES</varname>.</para> 111 <para>In this example, <varname>TEST</varname> would be <literal>osspecificvalue</literal>, due to the condition <quote>os</quote> being in <varname>OVERRIDES</varname>.</para>
98 </section> 112 </section>
99 <section> 113
114 <section id='conditional-appending'>
100 <title>Conditional appending</title> 115 <title>Conditional appending</title>
101 <para>BitBake also supports appending and prepending to variables based on whether something is in OVERRIDES. Example:</para> 116 <para>BitBake also supports appending and prepending to variables based on whether something is in OVERRIDES. Example:</para>
102 <para><screen><varname>DEPENDS</varname> = "glibc ncurses" 117 <para><screen><varname>DEPENDS</varname> = "glibc ncurses"
@@ -104,21 +119,24 @@ yourself.</para>
104<varname>DEPENDS_append_machine</varname> = " libmad"</screen></para> 119<varname>DEPENDS_append_machine</varname> = " libmad"</screen></para>
105 <para>In this example, <varname>DEPENDS</varname> is set to <literal>glibc ncurses libmad</literal>.</para> 120 <para>In this example, <varname>DEPENDS</varname> is set to <literal>glibc ncurses libmad</literal>.</para>
106 </section> 121 </section>
107 <section> 122
123 <section id='inclusion-directive'>
108 <title>Inclusion</title> 124 <title>Inclusion</title>
109 <para>Next, there is the <literal>include</literal> directive, which causes BitBake to parse whatever file you specify, and insert it at that location, which is not unlike <command>make</command>. However, if the path specified on the <literal>include</literal> line is a relative path, BitBake will locate the first one it can find within <envar>BBPATH</envar>.</para> 125 <para>Next, there is the <literal>include</literal> directive, which causes BitBake to parse whatever file you specify, and insert it at that location, which is not unlike <command>make</command>. However, if the path specified on the <literal>include</literal> line is a relative path, BitBake will locate the first one it can find within <envar>BBPATH</envar>.</para>
110 </section> 126 </section>
111 <section> 127 <section id='requiring-inclusion'>
112 <title>Requiring inclusion</title> 128 <title>Requiring inclusion</title>
113 <para>In contrast to the <literal>include</literal> directive, <literal>require</literal> will 129 <para>In contrast to the <literal>include</literal> directive, <literal>require</literal> will
114raise an ParseError if the file to be included cannot be found. Otherwise it will behave just like the <literal> 130raise an ParseError if the file to be included cannot be found. Otherwise it will behave just like the <literal>
115include</literal> directive.</para> 131include</literal> directive.</para>
116 </section> 132 </section>
117 <section> 133
134 <section id='inline-python-variable-expansion'>
118 <title>Python variable expansion</title> 135 <title>Python variable expansion</title>
119 <para><screen><varname>DATE</varname> = "${@time.strftime('%Y%m%d',time.gmtime())}"</screen></para> 136 <para><screen><varname>DATE</varname> = "${@time.strftime('%Y%m%d',time.gmtime())}"</screen></para>
120 <para>This would result in the <varname>DATE</varname> variable containing today's date.</para> 137 <para>This would result in the <varname>DATE</varname> variable containing today's date.</para>
121 </section> 138 </section>
139
122 <section> 140 <section>
123 <title>Defining executable metadata</title> 141 <title>Defining executable metadata</title>
124 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para> 142 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para>
@@ -132,7 +150,8 @@ include</literal> directive.</para>
132}</screen></para> 150}</screen></para>
133 <para>This is the similar to the previous, but flags it as Python so that BitBake knows it is Python code.</para> 151 <para>This is the similar to the previous, but flags it as Python so that BitBake knows it is Python code.</para>
134 </section> 152 </section>
135 <section> 153
154 <section id='defining-python-functions-into-the-global-python-namespace'>
136 <title>Defining Python functions into the global Python namespace</title> 155 <title>Defining Python functions into the global Python namespace</title>
137 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para> 156 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para>
138 <para><screen>def get_depends(bb, d): 157 <para><screen>def get_depends(bb, d):
@@ -145,17 +164,19 @@ include</literal> directive.</para>
145<varname>DEPENDS</varname> = "${@get_depends(bb, d)}"</screen></para> 164<varname>DEPENDS</varname> = "${@get_depends(bb, d)}"</screen></para>
146 <para>This would result in <varname>DEPENDS</varname> containing <literal>dependencywithcond</literal>.</para> 165 <para>This would result in <varname>DEPENDS</varname> containing <literal>dependencywithcond</literal>.</para>
147 </section> 166 </section>
148 <section> 167
168 <section id='variable-flags'>
149 <title>Variable flags</title> 169 <title>Variable flags</title>
150 <para>Variables can have associated flags which provide a way of tagging extra information onto a variable. Several flags are used internally by BitBake but they can be used externally too if needed. The standard operations mentioned above also work on flags.</para> 170 <para>Variables can have associated flags which provide a way of tagging extra information onto a variable. Several flags are used internally by BitBake but they can be used externally too if needed. The standard operations mentioned above also work on flags.</para>
151 <para><screen><varname>VARIABLE</varname>[<varname>SOMEFLAG</varname>] = "value"</screen></para> 171 <para><screen><varname>VARIABLE</varname>[<varname>SOMEFLAG</varname>] = "value"</screen></para>
152 <para>In this example, <varname>VARIABLE</varname> has a flag, <varname>SOMEFLAG</varname> which is set to <literal>value</literal>.</para> 172 <para>In this example, <varname>VARIABLE</varname> has a flag, <varname>SOMEFLAG</varname> which is set to <literal>value</literal>.</para>
153 </section> 173 </section>
154 <section> 174 <section id='inheritance-directive'>
155 <title>Inheritance</title> 175 <title>Inheritance</title>
156 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para> 176 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para>
157 <para>The <literal>inherit</literal> directive is a means of specifying what classes of functionality your .bb requires. It is a rudimentary form of inheritance. For example, you can easily abstract out the tasks involved in building a package that uses autoconf and automake, and put that into a bbclass for your packages to make use of. A given bbclass is located by searching for classes/filename.bbclass in <envar>BBPATH</envar>, where filename is what you inherited.</para> 177 <para>The <literal>inherit</literal> directive is a means of specifying what classes of functionality your .bb requires. It is a rudimentary form of inheritance. For example, you can easily abstract out the tasks involved in building a package that uses autoconf and automake, and put that into a bbclass for your packages to make use of. A given bbclass is located by searching for classes/filename.bbclass in <envar>BBPATH</envar>, where filename is what you inherited.</para>
158 </section> 178 </section>
179
159 <section> 180 <section>
160 <title>Tasks</title> 181 <title>Tasks</title>
161 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para> 182 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para>
@@ -169,7 +190,7 @@ addtask printdate before do_build</screen></para>
169 <para>This defines the necessary Python function and adds it as a task which is now a dependency of do_build, the default task. If anyone executes the do_build task, that will result in do_printdate being run first.</para> 190 <para>This defines the necessary Python function and adds it as a task which is now a dependency of do_build, the default task. If anyone executes the do_build task, that will result in do_printdate being run first.</para>
170 </section> 191 </section>
171 192
172 <section> 193 <section id='task-flags'>
173 <title>Task Flags</title> 194 <title>Task Flags</title>
174 <para>Tasks support a number of flags which control various functionality of the task. These are as follows:</para> 195 <para>Tasks support a number of flags which control various functionality of the task. These are as follows:</para>
175 <para>'dirs' - directories which should be created before the task runs</para> 196 <para>'dirs' - directories which should be created before the task runs</para>
@@ -181,7 +202,7 @@ addtask printdate before do_build</screen></para>
181 <para> For the 'deptask', 'rdeptask', 'depends', 'rdepends' and 'recrdeptask' flags please see the dependencies section.</para> 202 <para> For the 'deptask', 'rdeptask', 'depends', 'rdepends' and 'recrdeptask' flags please see the dependencies section.</para>
182 </section> 203 </section>
183 204
184 <section> 205 <section id='events'>
185 <title>Events</title> 206 <title>Events</title>
186 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para> 207 <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para>
187 <para>BitBake allows installation of event handlers. Events are triggered at certain points during operation, such as the beginning of operation against a given .bb, the start of a given task, task failure, task success, et cetera. The intent is to make it easy to do things like email notification on build failure.</para> 208 <para>BitBake allows installation of event handlers. Events are triggered at certain points during operation, such as the beginning of operation against a given .bb, the start of a given task, task failure, task success, et cetera. The intent is to make it easy to do things like email notification on build failure.</para>
@@ -198,7 +219,8 @@ This event handler gets called every time an event is triggered. A global variab
198method one can get the name of the triggered event.</para><para>The above event handler prints the name 219method one can get the name of the triggered event.</para><para>The above event handler prints the name
199of the event and the content of the <varname>FILE</varname> variable.</para> 220of the event and the content of the <varname>FILE</varname> variable.</para>
200 </section> 221 </section>
201 <section> 222
223 <section id='variants-class-extension-mechanism'>
202 <title>Variants</title> 224 <title>Variants</title>
203 <para>Two BitBake features exist to facilitate the creation of multiple buildable incarnations from a single recipe file.</para> 225 <para>Two BitBake features exist to facilitate the creation of multiple buildable incarnations from a single recipe file.</para>
204 <para>The first is <varname>BBCLASSEXTEND</varname>. This variable is a space separated list of classes used to "extend" the recipe for each variant. As an example, setting <screen>BBCLASSEXTEND = "native"</screen> results in a second incarnation of the current recipe being available. This second incarnation will have the "native" class inherited.</para> 226 <para>The first is <varname>BBCLASSEXTEND</varname>. This variable is a space separated list of classes used to "extend" the recipe for each variant. As an example, setting <screen>BBCLASSEXTEND = "native"</screen> results in a second incarnation of the current recipe being available. This second incarnation will have the "native" class inherited.</para>
@@ -212,7 +234,7 @@ SRC_URI_append_1.0.7+ = "file://some_patch_which_the_new_versions_need.patch;pat
212 </section> 234 </section>
213 </section> 235 </section>
214 236
215 <section> 237 <section id='variable-interaction-worked-examples'>
216 <title>Variable interaction: Worked Examples</title> 238 <title>Variable interaction: Worked Examples</title>
217 <para>Despite the documentation of the different forms of variable definition above, it can be hard to work out what happens when variable operators are combined. This section documents some common questions people have regarding the way variables interact.</para> 239 <para>Despite the documentation of the different forms of variable definition above, it can be hard to work out what happens when variable operators are combined. This section documents some common questions people have regarding the way variables interact.</para>
218 240
@@ -244,7 +266,8 @@ SRC_URI_append_1.0.7+ = "file://some_patch_which_the_new_versions_need.patch;pat
244 <para>Would ultimately result in <varname>A</varname> taking the value "1 4523" since the _append operator executes at the same time as the expansion of other overrides.</para> 266 <para>Would ultimately result in <varname>A</varname> taking the value "1 4523" since the _append operator executes at the same time as the expansion of other overrides.</para>
245 267
246 </section> 268 </section>
247 <section> 269
270 <section id='key-expansion'>
248 <title>Key Expansion</title> 271 <title>Key Expansion</title>
249 272
250 <para>Key expansion happens at the data store finalisation time just before overrides are expanded.</para> 273 <para>Key expansion happens at the data store finalisation time just before overrides are expanded.</para>
@@ -256,32 +279,35 @@ SRC_URI_append_1.0.7+ = "file://some_patch_which_the_new_versions_need.patch;pat
256 </section> 279 </section>
257 280
258 </section> 281 </section>
259 <section> 282 <section id='dependencies'>
260 <title>Dependency handling</title> 283 <title>Dependency handling</title>
261 <para>BitBake handles dependencies at the task level since to allow for efficient operation with multiple processed executing in parallel. A robust method of specifying task dependencies is therefore needed. </para> 284 <para>BitBake handles dependencies at the task level since to allow for efficient operation with multiple processed executing in parallel. A robust method of specifying task dependencies is therefore needed. </para>
262 <section> 285 <section id='dependencies-internal-to-the-bb-file'>
263 <title>Dependencies internal to the .bb file</title> 286 <title>Dependencies internal to the .bb file</title>
264 <para>Where the dependencies are internal to a given .bb file, the dependencies are handled by the previously detailed addtask directive.</para> 287 <para>Where the dependencies are internal to a given .bb file, the dependencies are handled by the previously detailed addtask directive.</para>
265 </section> 288 </section>
266 289
267 <section> 290 <section id='build-dependencies'>
268 <title>Build Dependencies</title> 291 <title>Build Dependencies</title>
269 <para>DEPENDS lists build time dependencies. The 'deptask' flag for tasks is used to signify the task of each item listed in DEPENDS which must have completed before that task can be executed.</para> 292 <para>DEPENDS lists build time dependencies. The 'deptask' flag for tasks is used to signify the task of each item listed in DEPENDS which must have completed before that task can be executed.</para>
270 <para><screen>do_configure[deptask] = "do_populate_staging"</screen></para> 293 <para><screen>do_configure[deptask] = "do_populate_staging"</screen></para>
271 <para>means the do_populate_staging task of each item in DEPENDS must have completed before do_configure can execute.</para> 294 <para>means the do_populate_staging task of each item in DEPENDS must have completed before do_configure can execute.</para>
272 </section> 295 </section>
273 <section> 296
297 <section id='runtime-dependencies'>
274 <title>Runtime Dependencies</title> 298 <title>Runtime Dependencies</title>
275 <para>The PACKAGES variable lists runtime packages and each of these can have RDEPENDS and RRECOMMENDS runtime dependencies. The 'rdeptask' flag for tasks is used to signify the task of each item runtime dependency which must have completed before that task can be executed.</para> 299 <para>The PACKAGES variable lists runtime packages and each of these can have RDEPENDS and RRECOMMENDS runtime dependencies. The 'rdeptask' flag for tasks is used to signify the task of each item runtime dependency which must have completed before that task can be executed.</para>
276 <para><screen>do_package_write[rdeptask] = "do_package"</screen></para> 300 <para><screen>do_package_write[rdeptask] = "do_package"</screen></para>
277 <para>means the do_package task of each item in RDEPENDS must have completed before do_package_write can execute.</para> 301 <para>means the do_package task of each item in RDEPENDS must have completed before do_package_write can execute.</para>
278 </section> 302 </section>
279 <section> 303
304 <section id='recursive-dependencies'>
280 <title>Recursive Dependencies</title> 305 <title>Recursive Dependencies</title>
281 <para>These are specified with the 'recrdeptask' flag which is used signify the task(s) of dependencies which must have completed before that task can be executed. It works by looking though the build and runtime dependencies of the current recipe as well as any inter-task dependencies the task has, then adding a dependency on the listed task. It will then recurse through the dependencies of those tasks and so on.</para> 306 <para>These are specified with the 'recrdeptask' flag which is used signify the task(s) of dependencies which must have completed before that task can be executed. It works by looking though the build and runtime dependencies of the current recipe as well as any inter-task dependencies the task has, then adding a dependency on the listed task. It will then recurse through the dependencies of those tasks and so on.</para>
282 <para>It may be desireable to recurse not just through the dependencies of those tasks but through the build and runtime dependencies of dependent tasks too. If that is the case, the taskname itself should be referenced in the task list, e.g. do_a[recrdeptask] = "do_a do_b".</para> 307 <para>It may be desireable to recurse not just through the dependencies of those tasks but through the build and runtime dependencies of dependent tasks too. If that is the case, the taskname itself should be referenced in the task list, e.g. do_a[recrdeptask] = "do_a do_b".</para>
283 </section> 308 </section>
284 <section> 309
310 <section id='inter-task-dependencies'>
285 <title>Inter task</title> 311 <title>Inter task</title>
286 <para>The 'depends' flag for tasks is a more generic form of which allows an interdependency on specific tasks rather than specifying the data in DEPENDS.</para> 312 <para>The 'depends' flag for tasks is a more generic form of which allows an interdependency on specific tasks rather than specifying the data in DEPENDS.</para>
287 <para><screen>do_patch[depends] = "quilt-native:do_populate_staging"</screen></para> 313 <para><screen>do_patch[depends] = "quilt-native:do_populate_staging"</screen></para>
@@ -290,20 +316,20 @@ SRC_URI_append_1.0.7+ = "file://some_patch_which_the_new_versions_need.patch;pat
290 </section> 316 </section>
291 </section> 317 </section>
292 318
293 <section> 319 <section id='parsing-overview'>
294 <title>Parsing</title> 320 <title>Parsing</title>
295 <section> 321 <section id='configiguration-files'>
296 <title>Configuration files</title> 322 <title>Configuration files</title>
297 <para>The first kind of metadata in BitBake is configuration metadata. This metadata is global, and therefore affects <emphasis>all</emphasis> packages and tasks which are executed.</para> 323 <para>The first kind of metadata in BitBake is configuration metadata. This metadata is global, and therefore affects <emphasis>all</emphasis> packages and tasks which are executed.</para>
298 <para>BitBake will first search the current working directory for an optional "conf/bblayers.conf" configuration file. This file is expected to contain a BBLAYERS variable which is a space delimited list of 'layer' directories. For each directory in this list, a "conf/layer.conf" file will be searched for and parsed with the LAYERDIR variable being set to the directory where the layer was found. The idea is these files will setup BBPATH and other variables correctly for a given build directory automatically for the user.</para> 324 <para>BitBake will first search the current working directory for an optional "conf/bblayers.conf" configuration file. This file is expected to contain a BBLAYERS variable which is a space delimited list of 'layer' directories. For each directory in this list, a "conf/layer.conf" file will be searched for and parsed with the LAYERDIR variable being set to the directory where the layer was found. The idea is these files will setup BBPATH and other variables correctly for a given build directory automatically for the user.</para>
299 <para>BitBake will then expect to find 'conf/bitbake.conf' somewhere in the user specified <envar>BBPATH</envar>. That configuration file generally has include directives to pull in any other metadata (generally files specific to architecture, machine, <emphasis>local</emphasis> and so on).</para> 325 <para>BitBake will then expect to find 'conf/bitbake.conf' somewhere in the user specified <envar>BBPATH</envar>. That configuration file generally has include directives to pull in any other metadata (generally files specific to architecture, machine, <emphasis>local</emphasis> and so on).</para>
300 <para>Only variable definitions and include directives are allowed in .conf files.</para> 326 <para>Only variable definitions and include directives are allowed in .conf files.</para>
301 </section> 327 </section>
302 <section> 328 <section id='classes'>
303 <title>Classes</title> 329 <title>Classes</title>
304 <para>BitBake classes are our rudimentary inheritance mechanism. As briefly mentioned in the metadata introduction, they're parsed when an <literal>inherit</literal> directive is encountered, and they are located in classes/ relative to the directories in <envar>BBPATH</envar>.</para> 330 <para>BitBake classes are our rudimentary inheritance mechanism. As briefly mentioned in the metadata introduction, they're parsed when an <literal>inherit</literal> directive is encountered, and they are located in classes/ relative to the directories in <envar>BBPATH</envar>.</para>
305 </section> 331 </section>
306 <section> 332 <section id='bb-files'>
307 <title>.bb files</title> 333 <title>.bb files</title>
308 <para>A BitBake (.bb) file is a logical unit of tasks to be executed. Normally this is a package to be built. Inter-.bb dependencies are obeyed. The files themselves are located via the <varname>BBFILES</varname> variable, which is set to a space separated list of .bb files, and does handle wildcards.</para> 334 <para>A BitBake (.bb) file is a logical unit of tasks to be executed. Normally this is a package to be built. Inter-.bb dependencies are obeyed. The files themselves are located via the <varname>BBFILES</varname> variable, which is set to a space separated list of .bb files, and does handle wildcards.</para>
309 </section> 335 </section>