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This is the raw text from Tom for the architecture chapter. No editing at all. (From yocto-docs rev: f402cc14ac7fef30460e130cc5bdfca731886aa3) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
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[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
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<chapter id='dev-manual-start'>
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<chapter id='profile-manual-arch'>
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<title>Getting Started with the Yocto Project</title>
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<title>Overall Architecture of the Linux Tracing and Profiling Tools</title>
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<para>
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This chapter introduces the Yocto Project and gives you an idea of what you need to get started.
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You can find enough information to set up your development host and build or use images for
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hardware supported by the Yocto Project by reading the
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<ulink url='&YOCTO_DOCS_QS_URL;'>Yocto Project Quick Start</ulink>.
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</para>
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<para>
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The remainder of this chapter summarizes what is in the Yocto Project Quick Start and provides
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some higher-level concepts you might want to consider.
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</para>
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<section id='introducing-the-yocto-project'>
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<title>Introducing the Yocto Project</title>
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<section id='architecture-of-the-tracing-and-profiling-tools'>
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<title>Architecture of the Tracing and Profiling Tools</title>
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<para>
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The Yocto Project is an open-source collaboration project focused on embedded Linux development.
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The project currently provides a build system, which is
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referred to as the OpenEmbedded build system in the Yocto Project documentation.
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The Yocto Project provides various ancillary tools suitable for the embedded developer
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and also features the Sato reference User Interface, which is optimized for
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stylus driven, low-resolution screens.
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It may seem surprising to see a section covering an 'overall architecture'
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for what seems to be a random collection of tracing tools that together
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make up the Linux tracing and profiling space.
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The fact is, however, that in recent years this seemingly disparate
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set of tools has started to converge on a 'core' set of underlying
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mechanisms:
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</para>
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|
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<para>
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You can use the OpenEmbedded build system, which uses
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BitBake to develop complete Linux
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||||
images and associated user-space applications for architectures based on ARM, MIPS, PowerPC,
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x86 and x86-64.
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While the Yocto Project does not provide a strict testing framework,
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it does provide or generate for you artifacts that let you perform target-level and
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emulated testing and debugging.
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Additionally, if you are an <trademark class='trade'>Eclipse</trademark>
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IDE user, you can install an Eclipse Yocto Plug-in to allow you to
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develop within that familiar environment.
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</para>
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</section>
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<section id='getting-setup'>
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<title>Getting Set Up</title>
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<para>
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Here is what you need to get set up to use the Yocto Project:
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<itemizedlist>
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||||
<listitem><para><emphasis>Host System:</emphasis> You should have a reasonably current
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||||
Linux-based host system.
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You will have the best results with a recent release of Fedora,
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OpenSUSE, Debian, Ubuntu, or CentOS as these releases are frequently tested against the Yocto Project
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||||
and officially supported.
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||||
For a list of the distributions under validation and their status, see the
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"<ulink url='&YOCTO_DOCS_REF_URL;#detailed-supported-distros'>Supported Linux Distributions</ulink>" section
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||||
in the Yocto Project Reference Manual and the wiki page at
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||||
<ulink url='&YOCTO_WIKI_URL;/wiki/Distribution_Support'>Distribution Support</ulink>.</para>
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<para>
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You should also have about 100 gigabytes of free disk space for building images.
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</para></listitem>
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<listitem><para><emphasis>Packages:</emphasis> The OpenEmbedded build system
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requires certain packages exist on your development system (e.g. Python 2.6 or 2.7).
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See "<ulink url='&YOCTO_DOCS_QS_URL;#packages'>The Packages</ulink>"
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section in the Yocto Project Quick Start for the exact package
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requirements and the installation commands to install them
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||||
for the supported distributions.</para></listitem>
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||||
<listitem id='local-yp-release'><para><emphasis>Yocto Project Release:</emphasis>
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You need a release of the Yocto Project.
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You set that up with a local <link linkend='source-directory'>Source Directory</link>
|
||||
one of two ways depending on whether you
|
||||
are going to contribute back into the Yocto Project or not.
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<note>
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Regardless of the method you use, this manual refers to the resulting local
|
||||
hierarchical set of files as the "Source Directory."
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</note>
|
||||
<itemizedlist>
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<listitem><para><emphasis>Tarball Extraction:</emphasis> If you are not going to contribute
|
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back into the Yocto Project, you can simply download a Yocto Project release you want
|
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from the website’s <ulink url='&YOCTO_HOME_URL;/download'>download page</ulink>.
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Once you have the tarball, just extract it into a directory of your choice.</para>
|
||||
<para>For example, the following command extracts the Yocto Project &DISTRO;
|
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release tarball
|
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into the current working directory and sets up the local Source Directory
|
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with a top-level folder named <filename>&YOCTO_POKY;</filename>:
|
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<literallayout class='monospaced'>
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||||
$ tar xfj &YOCTO_POKY_TARBALL;
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</literallayout></para>
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||||
<para>This method does not produce a local Git repository.
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Instead, you simply end up with a snapshot of the release.</para></listitem>
|
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<listitem><para><emphasis>Git Repository Method:</emphasis> If you are going to be contributing
|
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back into the Yocto Project or you simply want to keep up
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with the latest developments, you should use Git commands to set up a local
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Git repository of the upstream <filename>poky</filename> source repository.
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Doing so creates a repository with a complete history of changes and allows
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you to easily submit your changes upstream to the project.
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Because you cloned the repository, you have access to all the Yocto Project development
|
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branches and tag names used in the upstream repository.</para>
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<para>The following transcript shows how to clone the <filename>poky</filename>
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Git repository into the current working directory.
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<note>You can view the Yocto Project Source Repositories at
|
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<ulink url='&YOCTO_GIT_URL;/cgit.cgi'></ulink></note>
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The command creates the local repository in a directory named <filename>poky</filename>.
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For information on Git used within the Yocto Project, see the
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"<link linkend='git'>Git</link>" section.
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<literallayout class='monospaced'>
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$ git clone git://git.yoctoproject.org/poky
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Initialized empty Git repository in /home/scottrif/poky/.git/
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remote: Counting objects: 141863, done.
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remote: Compressing objects: 100% (38624/38624), done.
|
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remote: Total 141863 (delta 99661), reused 141816 (delta 99614)
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Receiving objects: 100% (141863/141863), 76.64 MiB | 126 KiB/s, done.
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Resolving deltas: 100% (99661/99661), done.
|
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</literallayout></para>
|
||||
<para>For another example of how to set up your own local Git repositories, see this
|
||||
<ulink url='&YOCTO_WIKI_URL;/wiki/Transcript:_from_git_checkout_to_meta-intel_BSP'>
|
||||
wiki page</ulink>, which describes how to create both <filename>poky</filename>
|
||||
and <filename>meta-intel</filename> Git repositories.</para></listitem>
|
||||
</itemizedlist></para></listitem>
|
||||
<listitem id='local-kernel-files'><para><emphasis>Yocto Project Kernel:</emphasis>
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||||
If you are going to be making modifications to a supported Yocto Project kernel, you
|
||||
need to establish local copies of the source.
|
||||
You can find Git repositories of supported Yocto Project Kernels organized under
|
||||
"Yocto Linux Kernel" in the Yocto Project Source Repositories at
|
||||
<ulink url='&YOCTO_GIT_URL;/cgit.cgi'></ulink>.</para>
|
||||
<para>This setup can involve creating a bare clone of the Yocto Project kernel and then
|
||||
copying that cloned repository.
|
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You can create the bare clone and the copy of the bare clone anywhere you like.
|
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For simplicity, it is recommended that you create these structures outside of the
|
||||
Source Directory (usually <filename>poky</filename>).</para>
|
||||
<para>As an example, the following transcript shows how to create the bare clone
|
||||
of the <filename>linux-yocto-3.4</filename> kernel and then create a copy of
|
||||
that clone.
|
||||
<note>When you have a local Yocto Project kernel Git repository, you can
|
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reference that repository rather than the upstream Git repository as
|
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part of the <filename>clone</filename> command.
|
||||
Doing so can speed up the process.</note></para>
|
||||
<para>In the following example, the bare clone is named
|
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<filename>linux-yocto-3.4.git</filename>, while the
|
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copy is named <filename>my-linux-yocto-3.4-work</filename>:
|
||||
<literallayout class='monospaced'>
|
||||
$ git clone --bare git://git.yoctoproject.org/linux-yocto-3.4 linux-yocto-3.4.git
|
||||
Initialized empty Git repository in /home/scottrif/linux-yocto-3.4.git/
|
||||
remote: Counting objects: 2468027, done.
|
||||
remote: Compressing objects: 100% (392255/392255), done.
|
||||
remote: Total 2468027 (delta 2071693), reused 2448773 (delta 2052498)
|
||||
Receiving objects: 100% (2468027/2468027), 530.46 MiB | 129 KiB/s, done.
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||||
Resolving deltas: 100% (2071693/2071693), done.
|
||||
</literallayout></para>
|
||||
<para>Now create a clone of the bare clone just created:
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<literallayout class='monospaced'>
|
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$ git clone linux-yocto-3.4.git my-linux-yocto-3.4-work
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||||
Cloning into 'my-linux-yocto-3.4-work'...
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done.
|
||||
</literallayout></para></listitem>
|
||||
<listitem id='poky-extras-repo'><para><emphasis>
|
||||
The <filename>poky-extras</filename> Git Repository</emphasis>:
|
||||
The <filename>poky-extras</filename> Git repository contains metadata needed
|
||||
only if you are modifying and building the kernel image.
|
||||
In particular, it contains the kernel BitBake append (<filename>.bbappend</filename>)
|
||||
files that you
|
||||
edit to point to your locally modified kernel source files and to build the kernel
|
||||
image.
|
||||
Pointing to these local files is much more efficient than requiring a download of the
|
||||
kernel's source files from upstream each time you make changes to the kernel.</para>
|
||||
<para>You can find the <filename>poky-extras</filename> Git Repository in the
|
||||
"Yocto Metadata Layers" area of the Yocto Project Source Repositories at
|
||||
<ulink url='&YOCTO_GIT_URL;/cgit.cgi'></ulink>.
|
||||
It is good practice to create this Git repository inside the Source Directory.</para>
|
||||
<para>Following is an example that creates the <filename>poky-extras</filename> Git
|
||||
repository inside the Source Directory, which is named <filename>poky</filename>
|
||||
in this case:
|
||||
<literallayout class='monospaced'>
|
||||
$ cd ~/poky
|
||||
$ git clone git://git.yoctoproject.org/poky-extras poky-extras
|
||||
Initialized empty Git repository in /home/scottrif/poky/poky-extras/.git/
|
||||
remote: Counting objects: 618, done.
|
||||
remote: Compressing objects: 100% (558/558), done.
|
||||
remote: Total 618 (delta 192), reused 307 (delta 39)
|
||||
Receiving objects: 100% (618/618), 526.26 KiB | 111 KiB/s, done.
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||||
Resolving deltas: 100% (192/192), done.
|
||||
</literallayout></para></listitem>
|
||||
<listitem><para id='supported-board-support-packages-(bsps)'><emphasis>Supported Board
|
||||
Support Packages (BSPs):</emphasis>
|
||||
The Yocto Project provides a layer called <filename>meta-intel</filename> and
|
||||
it is maintained in its own separate Git repository.
|
||||
The <filename>meta-intel</filename> layer contains many supported
|
||||
<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP Layers</ulink>.</para>
|
||||
<para>Similar considerations exist for setting up the <filename>meta-intel</filename>
|
||||
layer.
|
||||
You can get set up for BSP development one of two ways: tarball extraction or
|
||||
with a local Git repository.
|
||||
It is a good idea to use the same method that you used to set up the Source Directory.
|
||||
Regardless of the method you use, the Yocto Project uses the following BSP layer
|
||||
naming scheme:
|
||||
<literallayout class='monospaced'>
|
||||
meta-<BSP_name>
|
||||
</literallayout>
|
||||
where <filename><BSP_name></filename> is the recognized BSP name.
|
||||
Here are some examples:
|
||||
<literallayout class='monospaced'>
|
||||
meta-crownbay
|
||||
meta-emenlow
|
||||
meta-n450
|
||||
</literallayout>
|
||||
See the
|
||||
"<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP Layers</ulink>"
|
||||
section in the Yocto Project Board Support Package (BSP) Developer's Guide for more
|
||||
information on BSP Layers.
|
||||
<itemizedlist>
|
||||
<listitem><para><emphasis>Tarball Extraction:</emphasis> You can download any released
|
||||
BSP tarball from the same
|
||||
<ulink url='&YOCTO_HOME_URL;/download'>download site</ulink> used
|
||||
to get the Yocto Project release.
|
||||
Once you have the tarball, just extract it into a directory of your choice.
|
||||
Again, this method just produces a snapshot of the BSP layer in the form
|
||||
of a hierarchical directory structure.</para></listitem>
|
||||
<listitem><para><emphasis>Git Repository Method:</emphasis> If you are working
|
||||
with a local Git repository for your Source Directory, you should also use this method
|
||||
to set up the <filename>meta-intel</filename> Git repository.
|
||||
You can locate the <filename>meta-intel</filename> Git repository in the
|
||||
"Yocto Metadata Layers" area of the Yocto Project Source Repositories at
|
||||
<ulink url='&YOCTO_GIT_URL;/cgit.cgi'></ulink>.</para>
|
||||
<para>Typically, you set up the <filename>meta-intel</filename> Git repository inside
|
||||
the Source Directory.
|
||||
For example, the following transcript shows the steps to clone the
|
||||
<filename>meta-intel</filename>
|
||||
Git repository inside the local <filename>poky</filename> Git repository.
|
||||
<literallayout class='monospaced'>
|
||||
$ cd ~/poky
|
||||
$ git clone git://git.yoctoproject.org/meta-intel.git
|
||||
Initialized empty Git repository in /home/scottrif/poky/meta-intel/.git/
|
||||
remote: Counting objects: 3380, done.
|
||||
remote: Compressing objects: 100% (2750/2750), done.
|
||||
remote: Total 3380 (delta 1689), reused 227 (delta 113)
|
||||
Receiving objects: 100% (3380/3380), 1.77 MiB | 128 KiB/s, done.
|
||||
Resolving deltas: 100% (1689/1689), done.
|
||||
</literallayout></para>
|
||||
<para>The same
|
||||
<ulink url='&YOCTO_WIKI_URL;/wiki/Transcript:_from_git_checkout_to_meta-intel_BSP'>
|
||||
wiki page</ulink> referenced earlier covers how to
|
||||
set up the <filename>meta-intel</filename> Git repository.</para></listitem>
|
||||
</itemizedlist></para></listitem>
|
||||
<listitem><para><emphasis>Eclipse Yocto Plug-in:</emphasis> If you are developing
|
||||
applications using the Eclipse Integrated Development Environment (IDE),
|
||||
you will need this plug-in.
|
||||
See the
|
||||
"<link linkend='setting-up-the-eclipse-ide'>Setting up the Eclipse IDE</link>"
|
||||
section for more information.</para></listitem>
|
||||
<listitem>static tracepoints</listitem>
|
||||
<listitem>dynamic tracepoints
|
||||
<itemizedlist>
|
||||
<listitem>kprobes</listitem>
|
||||
<listitem>uprobes</listitem>
|
||||
</itemizedlist>
|
||||
</listitem>
|
||||
<listitem>the perf_events subsystem</listitem>
|
||||
<listitem>debugfs</listitem>
|
||||
</itemizedlist>
|
||||
</para>
|
||||
</section>
|
||||
|
||||
<section id='building-images'>
|
||||
<title>Building Images</title>
|
||||
|
||||
<para>
|
||||
The build process creates an entire Linux distribution, including the toolchain, from source.
|
||||
For more information on this topic, see the
|
||||
"<ulink url='&YOCTO_DOCS_QS_URL;#building-image'>Building an Image</ulink>"
|
||||
section in the Yocto Project Quick Start.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The build process is as follows:
|
||||
<orderedlist>
|
||||
<listitem><para>Make sure you have set up the Source Directory described in the
|
||||
previous section.</para></listitem>
|
||||
<listitem><para>Initialize the build environment by sourcing a build environment
|
||||
script.</para></listitem>
|
||||
<listitem><para>Optionally ensure the <filename>conf/local.conf</filename> configuration file,
|
||||
which is found in the
|
||||
<link linkend='build-directory'>Build Directory</link>,
|
||||
is set up how you want it.
|
||||
This file defines many aspects of the build environment including
|
||||
the target machine architecture through the
|
||||
<filename><ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'>MACHINE</ulink></filename> variable,
|
||||
the development machine's processor use through the
|
||||
<filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BB_NUMBER_THREADS'>BB_NUMBER_THREADS</ulink></filename> and
|
||||
<filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'>PARALLEL_MAKE</ulink></filename> variables, and
|
||||
a centralized tarball download directory through the
|
||||
<filename><ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'>DL_DIR</ulink></filename> variable.</para></listitem>
|
||||
<listitem><para>Build the image using the <filename>bitbake</filename> command.
|
||||
If you want information on BitBake, see the user manual inculded in the
|
||||
<filename>bitbake/doc/manual</filename> directory of the
|
||||
<link linkend='source-directory'>Source Directory</link>.</para></listitem>
|
||||
<listitem><para>Run the image either on the actual hardware or using the QEMU
|
||||
emulator.</para></listitem>
|
||||
</orderedlist>
|
||||
</para>
|
||||
</section>
|
||||
|
||||
<section id='using-pre-built-binaries-and-qemu'>
|
||||
<title>Using Pre-Built Binaries and QEMU</title>
|
||||
|
||||
<para>
|
||||
Another option you have to get started is to use pre-built binaries.
|
||||
The Yocto Project provides many types of binaries with each release.
|
||||
See the "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>"
|
||||
chapter in the Yocto Project Reference Manual
|
||||
for descriptions of the types of binaries that ship with a Yocto Project
|
||||
release.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Using a pre-built binary is ideal for developing software applications to run on your
|
||||
target hardware.
|
||||
To do this, you need to be able to access the appropriate cross-toolchain tarball for
|
||||
the architecture on which you are developing.
|
||||
If you are using an SDK type image, the image ships with the complete toolchain native to
|
||||
the architecture.
|
||||
If you are not using an SDK type image, you need to separately download and
|
||||
install the stand-alone Yocto Project cross-toolchain tarball.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Regardless of the type of image you are using, you need to download the pre-built kernel
|
||||
that you will boot in the QEMU emulator and then download and extract the target root
|
||||
filesystem for your target machine’s architecture.
|
||||
You can get architecture-specific binaries and filesystems from
|
||||
<ulink url='&YOCTO_MACHINES_DL_URL;'>machines</ulink>.
|
||||
You can get installation scripts for stand-alone toolchains from
|
||||
<ulink url='&YOCTO_TOOLCHAIN_DL_URL;'>toolchains</ulink>.
|
||||
Once you have all your files, you set up the environment to emulate the hardware
|
||||
by sourcing an environment setup script.
|
||||
Finally, you start the QEMU emulator.
|
||||
You can find details on all these steps in the
|
||||
"<ulink url='&YOCTO_DOCS_QS_URL;#using-pre-built'>Using Pre-Built Binaries and QEMU</ulink>"
|
||||
section of the Yocto Project Quick Start.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Using QEMU to emulate your hardware can result in speed issues
|
||||
depending on the target and host architecture mix.
|
||||
For example, using the <filename>qemux86</filename> image in the emulator
|
||||
on an Intel-based 32-bit (x86) host machine is fast because the target and
|
||||
host architectures match.
|
||||
On the other hand, using the <filename>qemuarm</filename> image on the same Intel-based
|
||||
host can be slower.
|
||||
But, you still achieve faithful emulation of ARM-specific issues.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
To speed things up, the QEMU images support using <filename>distcc</filename>
|
||||
to call a cross-compiler outside the emulated system.
|
||||
If you used <filename>runqemu</filename> to start QEMU, and the
|
||||
<filename>distccd</filename> application is present on the host system, any
|
||||
BitBake cross-compiling toolchain available from the build system is automatically
|
||||
used from within QEMU simply by calling <filename>distcc</filename>.
|
||||
You can accomplish this by defining the cross-compiler variable
|
||||
(e.g. <filename>export CC="distcc"</filename>).
|
||||
Alternatively, if you are using a suitable SDK image or the appropriate
|
||||
stand-alone toolchain is present in <filename>/opt/poky</filename>,
|
||||
the toolchain is also automatically used.
|
||||
</para>
|
||||
|
||||
<note>
|
||||
Several mechanisms exist that let you connect to the system running on the
|
||||
QEMU emulator:
|
||||
<itemizedlist>
|
||||
<listitem><para>QEMU provides a framebuffer interface that makes standard
|
||||
consoles available.</para></listitem>
|
||||
<listitem><para>Generally, headless embedded devices have a serial port.
|
||||
If so, you can configure the operating system of the running image
|
||||
to use that port to run a console.
|
||||
The connection uses standard IP networking.</para></listitem>
|
||||
<listitem><para>SSH servers exist in some QEMU images.
|
||||
The <filename>core-image-sato</filename> QEMU image has a Dropbear secure
|
||||
shell (ssh) server that runs with the root password disabled.
|
||||
The <filename>core-image-basic</filename> and <filename>core-image-lsb</filename> QEMU images
|
||||
have OpenSSH instead of Dropbear.
|
||||
Including these SSH servers allow you to use standard <filename>ssh</filename> and
|
||||
<filename>scp</filename> commands.
|
||||
The <filename>core-image-minimal</filename> QEMU image, however, contains no ssh
|
||||
server.</para></listitem>
|
||||
<listitem><para>You can use a provided, user-space NFS server to boot the QEMU session
|
||||
using a local copy of the root filesystem on the host.
|
||||
In order to make this connection, you must extract a root filesystem tarball by using the
|
||||
<filename>runqemu-extract-sdk</filename> command.
|
||||
After running the command, you must then point the <filename>runqemu</filename>
|
||||
script to the extracted directory instead of a root filesystem image file.</para></listitem>
|
||||
</itemizedlist>
|
||||
Tying It Together: Rather than enumerating here how each tool makes use of
|
||||
these common mechanisms, textboxes like this will make note of the
|
||||
specific usages in each tool as they come up in the course
|
||||
of the text.
|
||||
</note>
|
||||
</section>
|
||||
</chapter>
|
||||
|
|
|
|||
Loading…
Reference in New Issue