aboutsummaryrefslogtreecommitdiffstats
path: root/doc/user-manual/user-manual-intro.xml
diff options
context:
space:
mode:
Diffstat (limited to 'doc/user-manual/user-manual-intro.xml')
-rw-r--r--doc/user-manual/user-manual-intro.xml50
1 files changed, 50 insertions, 0 deletions
diff --git a/doc/user-manual/user-manual-intro.xml b/doc/user-manual/user-manual-intro.xml
new file mode 100644
index 000000000..824dee64e
--- /dev/null
+++ b/doc/user-manual/user-manual-intro.xml
@@ -0,0 +1,50 @@
+<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+ <chapter>
+ <title>Introduction</title>
+ <section>
+ <title>Overview</title>
+ <para>BitBake is, at its simplest, a tool for executing
+tasks and managing metadata. As such, its similarities to GNU make and other
+build tools are readily apparent. It was inspired by Portage, the package management system used by the Gentoo Linux distribution. BitBake is the basis of the <ulink url="http://www.openembedded.org/">OpenEmbedded</ulink> project, which is being used to build and maintain a number of embedded Linux distributions/projects such as Angstrom and the Yocto project.</para>
+ </section>
+ <section>
+ <title>Background and goals</title>
+ <para>Prior to BitBake, no other build tool adequately met
+the needs of an aspiring embedded Linux distribution. All of the
+buildsystems used by traditional desktop Linux distributions lacked
+important functionality, and none of the ad-hoc
+<emphasis>buildroot</emphasis> systems, prevalent in the
+embedded space, were scalable or maintainable.</para>
+
+ <para>Some important original goals for BitBake were:
+ <itemizedlist>
+ <listitem><para>Handle crosscompilation.</para></listitem>
+ <listitem><para>Handle interpackage dependencies (build time on target architecture, build time on native architecture, and runtime).</para></listitem>
+ <listitem><para>Support running any number of tasks within a given package, including, but not limited to, fetching upstream sources, unpacking them, patching them, configuring them, et cetera.</para></listitem>
+ <listitem><para>Must be Linux distribution agnostic (both build and target).</para></listitem>
+ <listitem><para>Must be architecture agnostic</para></listitem>
+ <listitem><para>Must support multiple build and target operating systems (including Cygwin, the BSDs, etc).</para></listitem>
+ <listitem><para>Must be able to be self contained, rather than tightly integrated into the build machine's root filesystem.</para></listitem>
+ <listitem><para>There must be a way to handle conditional metadata (on target architecture, operating system, distribution, machine).</para></listitem>
+ <listitem><para>It must be easy for the person using the tools to supply their own local metadata and packages to operate against.</para></listitem>
+ <listitem><para>Must make it easy to collaborate
+between multiple projects using BitBake for their
+builds.</para></listitem>
+ <listitem><para>Should provide an inheritance mechanism to
+share common metadata between many packages.</para></listitem>
+ </itemizedlist>
+ </para>
+ <para>Over time it has become apparent that some further requirements were necessary:
+ <itemizedlist>
+ <listitem><para>Handle variants of a base recipe (native, sdk, multilib).</para></listitem>
+ <listitem><para>Able to split metadata into layers and allow layers to override each other.</para></listitem>
+ <listitem><para>Allow representation of a given set of input variables to a task as a checksum.</para></listitem>
+ <listitem><para>based on that checksum, allow acceleration of builds with prebuilt components.</para></listitem>
+ </itemizedlist>
+ </para>
+
+ <para>BitBake satisfies all the original requirements and many more with extensions being made to the basic functionality to reflect the additionl requirements. Flexibility and power have always been the priorities. It is highly extensible, supporting embedded Python code and execution of any arbitrary tasks.</para>
+ </section>
+ </chapter>
+