<para>
The primary purpose for running BitBake is to produce some kind
- of output such as an image, a kernel, or a software development
- kit.
+ of output such as a single installable package, a kernel, a software
+ development kit, or even a full, board-specific bootable Linux image.
Of course, you can execute the <filename>bitbake</filename>
command with options that cause it to execute single tasks,
compile single recipe files, capture or clear data, or simply
see
"<link linkend='bitbake-user-manual-command'>The BitBake Command</link>"
section.
- </para>
+ <note>
+ <para>
+ Prior to executing BitBake, you should take advantage of available
+ parallel thread execution on your build host by setting the
+ <link linkend='var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></link>
+ variable in your project's <filename>local.conf</filename>
+ configuration file.
+ </para>
- <note>
- Prior to executing BitBake, you should take advantage of parallel
- thread execution by setting the
- <link linkend='var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></link>
- variable in your <filename>local.conf</filename>
- configuration file.
- </note>
+ <para>
+ A common way to determine this value for your build host is to run:
+ <literallayout class='monospaced'>
+ $ grep processor /proc/cpuinfo
+ </literallayout>
+ and count the number of processors displayed. Note that the number of
+ processors will take into account hyper-threading, so that a quad-core
+ build host with hyper-threading will most likely show eight processors,
+ which is the value you would then assign to that variable.
+ </para>
+ </note>
+ </para>
<section id='parsing-the-base-configuration-metadata'>
<title>Parsing the Base Configuration Metadata</title>
<para>
The first thing BitBake does is parse base configuration
metadata.
- Base configuration metadata consists of the
+ Base configuration metadata consists of your project's
<filename>bblayers.conf</filename> file to determine what
layers BitBake needs to recognize, all necessary
<filename>layer.conf</filename> files (one from each layer),
and
<link linkend='var-BBFILES'><filename>BBFILES</filename></link>.
<filename>BBPATH</filename> is used to search for
- configuration and class files under
- <filename>conf/</filename> and <filename>classes/</filename>
+ configuration and class files under the
+ <filename>conf</filename> and <filename>classes</filename>
directories, respectively.
- <filename>BBFILES</filename> is used to find recipe files
+ <filename>BBFILES</filename> is used to locate both recipe
+ and recipe append files
(<filename>.bb</filename> and <filename>.bbappend</filename>).
If there is no <filename>bblayers.conf</filename> file,
it is assumed the user has set the <filename>BBPATH</filename>
</para>
<para>
- Next, the <filename>bitbake.conf</filename> file is searched
+ Next, the <filename>bitbake.conf</filename> file is located
using the <filename>BBPATH</filename> variable that was
just constructed.
The <filename>bitbake.conf</filename> file may also include other
optional <filename>conf/bblayers.conf</filename> configuration file.
This file is expected to contain a
<link linkend='var-BBLAYERS'><filename>BBLAYERS</filename></link>
- variable that is a space delimited list of 'layer' directories.
+ variable that is a space-delimited list of 'layer' directories.
Recall that if BitBake cannot find a <filename>bblayers.conf</filename>
- file then it is assumed the user has set the <filename>BBPATH</filename>
+ file, then it is assumed the user has set the <filename>BBPATH</filename>
and <filename>BBFILES</filename> variables directly in the environment.
</para>
<para>
For each directory (layer) in this list, a <filename>conf/layer.conf</filename>
- file is searched for and parsed with the
+ file is located and parsed with the
<link linkend='var-LAYERDIR'><filename>LAYERDIR</filename></link>
variable being set to the directory where the layer was found.
The idea is these files automatically set up
<para>
Only variable definitions and include directives are allowed
- in <filename>.conf</filename> files.
+ in BitBake <filename>.conf</filename> files.
Some variables directly influence BitBake's behavior.
These variables might have been set from the environment
depending on the environment variables previously
Other classes that are specified in the configuration using the
<link linkend='var-INHERIT'><filename>INHERIT</filename></link>
variable are also included.
- BitBake searches for class files in a "classes" subdirectory under
+ BitBake searches for class files in a
+ <filename>classes</filename> subdirectory under
the paths in <filename>BBPATH</filename> in the same way as
configuration files.
</para>
If a recipe uses a closing curly brace within the function and
the character has no leading spaces, BitBake produces a parsing
error.
- If you use a pair of curly brace in a shell function, the
+ If you use a pair of curly braces in a shell function, the
closing curly brace must not be located at the start of the line
without leading spaces.
</para>
One common convention is to use the recipe filename to define
pieces of metadata.
For example, in <filename>bitbake.conf</filename> the recipe
- name and version set
+ name and version are used to set the variables
<link linkend='var-PN'><filename>PN</filename></link> and
<link linkend='var-PV'><filename>PV</filename></link>:
<literallayout class='monospaced'>
- PV = "${@bb.parse.BBHandler.vars_from_file(d.getVar('FILE'),d)[1] or '1.0'}"
PN = "${@bb.parse.BBHandler.vars_from_file(d.getVar('FILE'),d)[0] or 'defaultpkgname'}"
+ PV = "${@bb.parse.BBHandler.vars_from_file(d.getVar('FILE'),d)[1] or '1.0'}"
</literallayout>
- In this example, a recipe called "something_1.2.3.bb" sets
+ In this example, a recipe called "something_1.2.3.bb" would set
<filename>PN</filename> to "something" and
<filename>PV</filename> to "1.2.3".
</para>
projects / scm / bb / tizen-distro.git / commitdiff