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| -rw-r--r-- | documentation/poky-ref-manual/ref-bitbake.xml | 82 |
1 files changed, 41 insertions, 41 deletions
diff --git a/documentation/poky-ref-manual/ref-bitbake.xml b/documentation/poky-ref-manual/ref-bitbake.xml index 6221a963d8..9554c11388 100644 --- a/documentation/poky-ref-manual/ref-bitbake.xml +++ b/documentation/poky-ref-manual/ref-bitbake.xml @@ -6,32 +6,34 @@ <title>Reference: BitBake</title> <para> - BitBake is a program written in Python that interprets the metadata - that makes up Poky. At some point, people wonder what actually happens - when you type <command>bitbake poky-image-sato</command>. This section - aims to give an overview of what happens behind the scenes from a - BitBake perspective. + BitBake is a program written in Python that interprets the metadata that makes up Poky. + At some point, people wonder what actually happens when you enter: + <literallayout class='monospaced'> + $ bitbake poky-image-sato + </literallayout> </para> - + <para> - It is worth noting that BitBake aims to be a generic "task" executor - capable of handling complex dependency relationships. As such it has no - real knowledge of what the tasks it is executing actually do. It just - considers a list of tasks with dependencies and handles metadata - consisting of variables in a certain format which get passed to the - tasks. + This appendix provides an overview of what happens behind the scenes from BitBake's perspective. </para> + <note><para> + BitBake strives to be a generic "task" executor that is capable of handling complex dependency relationships. + As such, it has no real knowledge of what the tasks being executed actually do. + BitBake just considers a list of tasks with dependencies and handles metadata + that consists of variables in a certain format that get passed to the tasks. + </para></note> + <section id='ref-bitbake-parsing'> <title>Parsing</title> <para> The first thing BitBake does is work out its configuration by looking for a file called <filename>bitbake.conf</filename>. - BitBake searches through the <varname>BBPATH</varname> environment + BitBake examines the <varname>BBPATH</varname> environment variable looking for a <filename class="directory">conf/</filename> - directory containing a <filename>bitbake.conf</filename> file and - adds the first <filename>bitbake.conf</filename> file found in + directory that contains a <filename>bitbake.conf</filename> file. + BitBake adds the first <filename>bitbake.conf</filename> file found in <varname>BBPATH</varname> (similar to the PATH environment variable). For Poky, <filename>bitbake.conf</filename> is found in <filename class="directory">meta/conf/</filename>. @@ -42,32 +44,32 @@ files to include from a <filename class="directory">conf/</filename> directory below the directories listed in <varname>BBPATH</varname>. In general the most important configuration file from a user's perspective - is <filename>local.conf</filename>, which contains a users customized - settings for Poky. Other notable configuration files are the distribution + is <filename>local.conf</filename>, which contains a user's customized + settings for Poky. + Other notable configuration files are the distribution configuration file (set by the <glossterm><link linkend='var-DISTRO'> DISTRO</link></glossterm> variable) and the machine configuration file (set by the <glossterm><link linkend='var-MACHINE'>MACHINE</link> - </glossterm> variable). The <glossterm><link linkend='var-DISTRO'> - DISTRO</link></glossterm> and <glossterm><link linkend='var-MACHINE'> - MACHINE</link></glossterm> environment variables are both usually set in - the <filename>local.conf</filename> file. Valid distribution + </glossterm> variable). + The DISTRO and MACHINE environment variables are both usually set in + the <filename>local.conf</filename> file. + Valid distribution configuration files are available in the <filename class="directory"> meta/conf/distro/</filename> directory and valid machine configuration files in the <filename class="directory">meta/conf/machine/</filename> - directory. Within the <filename class="directory"> - meta/conf/machine/include/</filename> directory are various <filename> - tune-*.inc</filename> configuration files which provide common - "tuning" settings specific to and shared between particular - architectures and machines. + directory. + Within the <filename class="directory">meta/conf/machine/include/</filename> + directory are various <filename>tune-*.inc</filename> configuration files that provide common + "tuning" settings specific to and shared between particular architectures and machines. </para> <para> - After the parsing of the configuration files some standard classes - are included. In particular, <filename>base.bbclass</filename> is - always included, as will any other classes - specified in the configuration using the <glossterm><link - linkend='var-INHERIT'>INHERIT</link></glossterm> - variable. Class files are searched for in a classes subdirectory + After the parsing of the configuration files some standard classes are included. + The <filename>base.bbclass</filename> file is always included. + Other classes that are specified in the configuration using the + <glossterm><link linkend='var-INHERIT'>INHERIT</link></glossterm> + variable are also inculded. + Class files are searched for in a classes subdirectory under the paths in <varname>BBPATH</varname> in the same way as configuration files. </para> @@ -77,21 +79,19 @@ variable <glossterm><link linkend='var-BBFILES'>BBFILES</link></glossterm> is set, usually in <filename>local.conf</filename>, and defines the list of places to search for - <filename class="extension">.bb</filename> files. By - default this specifies the <filename class="directory">meta/packages/ + <filename class="extension">.bb</filename> files. + By default this specifies the <filename class="directory">meta/packages/ </filename> directory within Poky, but other directories such as <filename class="directory">meta-extras/</filename> can be included - too. Adding extra content to - <glossterm><link linkend='var-BBFILES'>BBFILES</link></glossterm> is best - acheived through the use of BitBake + too. + Adding extra content to BBFILES is best acheived through the use of BitBake <link linkend='usingpoky-changes-layers'>"layers"</link>. </para> <para> - BitBake parses each <filename class="extension">.bb</filename> file in - <glossterm><link linkend='var-BBFILES'>BBFILES</link></glossterm> and - stores the values of various variables. In summary, for each - <filename class="extension">.bb</filename> + BitBake parses each <filename class="extension">.bb</filename> file in BBFILES and + stores the values of various variables. + In summary, for each <filename class="extension">.bb</filename> file the configuration + base class of variables are set, followed by the data in the <filename class="extension">.bb</filename> file itself, followed by any inherit commands that |