777 lines
38 KiB
XML
777 lines
38 KiB
XML
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<chapter id='bsp'>
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<title>Board Support Packages (BSP) - Developer's Guide</title>
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<para>
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A Board Support Package (BSP) is a collection of information that
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defines how to support a particular hardware device, set of devices, or
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hardware platform.
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The BSP includes information about the hardware features
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present on the device and kernel configuration information along with any
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additional hardware drivers required.
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The BSP also lists any additional software
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components required in addition to a generic Linux software stack for both
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essential and optional platform features.
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</para>
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<para>
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This section (or document if you are reading the BSP Developer's Guide) defines
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a structure for these components
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so that BSPs follow a commonly understood layout.
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Providing a common form allows end-users to understand and become familiar
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with the layout.
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A common form also encourages standardization
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of software support of hardware.
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</para>
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<note>
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The information here does not provide an example of how to create a BSP.
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For examples on how to create a BSP, see the
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"<ulink url='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#dev-manual-bsp-appendix'>BSP Development Example</ulink>"
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section in The Yocto Project Development Manual.
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You can also see the
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<ulink url='https://wiki.yoctoproject.org/wiki/Transcript:_creating_one_generic_Atom_BSP_from_another'>
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wiki page</ulink>.
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</note>
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<para>
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The proposed format does have elements that are specific to the Yocto Project and
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OpenEmbedded build systems.
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It is intended that this information can be
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used by other systems besides Yocto Project and OpenEmbedded and that it will be simple
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to extract information and convert it to other formats if required.
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Yocto Project, through its standard layers mechanism, can directly accept the format
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described as a layer.
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The BSP captures all
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the hardware-specific details in one place in a standard format, which is
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useful for any person wishing to use the hardware platform regardless of
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the build system they are using.
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</para>
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<para>
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The BSP specification does not include a build system or other tools -
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it is concerned with the hardware-specific components only.
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At the end-distribution point, you can ship the BSP combined with a build system
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and other tools.
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However, it is important to maintain the distinction that these
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are separate components that happen to be combined in certain end products.
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</para>
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<section id='bsp-layers'>
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<title>BSP Layers</title>
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<para>
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The BSP consists of a file structure inside a base directory.
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Collectively, you can think of the base directory and the file structure
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as a BSP Layer.
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BSP Layers use the following naming convention:
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<literallayout class='monospaced'>
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meta-<bsp_name>
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</literallayout>
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"bsp_name" is a placeholder for the machine or platform name.
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</para>
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<para>
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The Yocto Project organizes BSP Layers within the Yocto Metadata Layers area
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of the Yocto Project Source Repositories at
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<ulink url='http://git.yoctoproject.org/cgit.cgi'></ulink>.
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If you examine the source repositories, you will find many BSP Layers.
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Here are a few:
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<literallayout class='monospaced'>
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meta-baryon
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meta-fsl-ppc
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meta-intel
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meta-selinux
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meta-ti
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</literallayout>
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It is worth noting that the <filename>meta-intel</filename> BSP Layer contains
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within itself several other BSP Layers, which makes it sort of a "super" BSP layer.
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Following is a sampling of the BSP Layers that the <filename>meta-intel</filename>
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BSP Layer contains:
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<literallayout class='monospaced'>
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meta-cedartrail
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meta-crownbay
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meta-emenlow
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meta-fishriver
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meta-fri2
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</literallayout>
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</para>
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<para>
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The layer's base directory (<filename>meta-<bsp_name></filename>) is the root
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of the BSP Layer.
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This root is what you add to the <filename>BBLAYERS</filename>
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variable in the <filename>conf/bblayers.conf</filename> file found in the
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<ulink url='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#yocto-project-build-directory'>Yocto Project Build Directory</ulink>.
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Adding the root allows the Yocto Project build system to recognize the BSP
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definition and from it build an image.
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Here is an example:
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<literallayout class='monospaced'>
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BBLAYERS = " \
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/usr/local/src/yocto/meta \
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/usr/local/src/yocto/meta-yocto \
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/usr/local/src/yocto/meta-<bsp_name> \
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"
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</literallayout>
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</para>
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<para>
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For more detailed information on layers, see the
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"<ulink url='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>"
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section of the Yocto Project Development Manual.
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You can also see the detailed examples in the appendices of
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<ulink url='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html'>
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The Yocto Project Development Manual</ulink>.
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</para>
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</section>
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<section id="bsp-filelayout">
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<title>Example Filesystem Layout</title>
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<para>
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Below is the common form for the file structure inside a BSP Layer.
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While you can use this basic form for the standard, realize that the actual structures
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for specific BSPs could differ.
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<literallayout class='monospaced'>
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meta-<bsp_name>/
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meta-<bsp_name>/<bsp_license_file>
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meta-<bsp_name>/README
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meta-<bsp_name>/binary/<bootable_images>
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meta-<bsp_name>/conf/layer.conf
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meta-<bsp_name>/conf/machine/*.conf
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meta-<bsp_name>/recipes-bsp/*
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meta-<bsp_name>/recipes-graphics/*
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meta-<bsp_name>/recipes-kernel/linux/linux-yocto_<kernel_rev>.bbappend
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</literallayout>
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</para>
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<para>
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Below is an example of the Crown Bay BSP:
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<literallayout class='monospaced'>
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meta-crownbay/COPYING.MIT
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meta-crownbay/README
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meta-crownbay/README.sources
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meta-crownbay/binary
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meta-crownbay/conf/
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meta-crownbay/conf/layer.conf
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meta-crownbay/conf/machine/
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meta-crownbay/conf/machine/crownbay.conf
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meta-crownbay/conf/machine/crownbay-noemgd.conf
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meta-crownbay/recipes-bsp/
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meta-crownbay/recipes-bsp/formfactor/
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meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend
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meta-crownbay/recipes-bsp/formfactor/formfactor/
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meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/
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meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig
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meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/
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meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/machconfig
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meta-crownbay/recipes-core
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meta-crownbay/recipes-core/tasks
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meta-crownbay/recipes-core/tasks/task-core-tools-profile.bbappend
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meta-crownbay/recipes-graphics/
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meta-crownbay/recipes-graphics/xorg-xserver/
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meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend
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meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/
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meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/
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meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xorg.conf
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meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/
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meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/xorg.conf
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meta-crownbay/recipes-kernel/
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meta-crownbay/recipes-kernel/linux/
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meta-crownbay/recipes-kernel/linux/linux-yocto-rt_3.0.bbappend
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meta-crownbay/recipes-kernel/linux/linux-yocto_2.6.37.bbappend
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meta-crownbay/recipes-kernel/linux/linux-yocto_3.0.bbappend
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</literallayout>
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</para>
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<para>
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The following sections describe each part of the proposed BSP format.
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</para>
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<section id="bsp-filelayout-license">
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<title>License Files</title>
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<para>
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You can find these files in the BSP Layer at:
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<literallayout class='monospaced'>
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meta-<bsp_name>/<bsp_license_file>
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</literallayout>
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</para>
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<para>
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These optional files satisfy licensing requirements for the BSP.
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The type or types of files here can vary depending on the licensing requirements.
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For example, in the Crown Bay BSP all licensing requirements are handled with the
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<filename>COPYING.MIT</filename> file.
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</para>
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<para>
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Licensing files can be MIT, BSD, GPLv*, and so forth.
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These files are recommended for the BSP but are optional and totally up to the BSP developer.
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</para>
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</section>
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<section id="bsp-filelayout-readme">
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<title>README File</title>
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<para>
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You can find this file in the BSP Layer at:
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<literallayout class='monospaced'>
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meta-<bsp_name>/README
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</literallayout>
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</para>
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<para>
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This file provides information on how to boot the live images that are optionally
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included in the <filename>/binary</filename> directory.
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The <filename>README</filename> file also provides special information needed for
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building the image.
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</para>
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<para>
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Technically speaking a <filename>README</filename> file is optional but it is highly
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recommended that every BSP has one.
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</para>
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</section>
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<section id="bsp-filelayout-readme-sources">
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<title>README.sources File</title>
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<para>
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You can find this file in the BSP Layer at:
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<literallayout class='monospaced'>
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meta-<bsp_name>/README.sources
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</literallayout>
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</para>
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<para>
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This file provides information on where to locate the BSP source files.
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For example, information provides where to find the sources that comprise
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the images shipped with the BSP.
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Information is also included to help you find the metadata used to generate the images
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that ship with the BSP.
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</para>
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<para>
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Technically speaking a <filename>README.sources</filename> file is optional but it is highly
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recommended that every BSP has one.
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</para>
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</section>
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<section id="bsp-filelayout-binary">
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<title>Pre-built User Binaries</title>
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<para>
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You can find these files in the BSP Layer at:
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<literallayout class='monospaced'>
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meta-<bsp_name>/binary/<bootable_images>
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</literallayout>
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</para>
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<para>
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This optional area contains useful pre-built kernels and user-space filesystem
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images appropriate to the target system.
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This directory typically contains graphical (e.g. sato) and minimal live images
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when the BSP tarball has been created and made available in the
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<ulink url='http://www.yoctoproject.org'>Yocto Project</ulink> website.
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You can use these kernels and images to get a system running and quickly get started
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on development tasks.
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</para>
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<para>
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The exact types of binaries present are highly hardware-dependent.
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However, a README file should be present in the BSP Layer that explains how to use
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the kernels and images with the target hardware.
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If pre-built binaries are present, source code to meet licensing requirements must also
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exist in some form.
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</para>
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</section>
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<section id='bsp-filelayout-layer'>
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<title>Layer Configuration File</title>
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<para>
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You can find this file in the BSP Layer at:
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<literallayout class='monospaced'>
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meta-<bsp_name>/conf/layer.conf
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</literallayout>
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</para>
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<para>
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The <filename>conf/layer.conf</filename> file identifies the file structure as a Yocto
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Project layer, identifies the
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contents of the layer, and contains information about how Yocto Project should use it.
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Generally, a standard boilerplate file such as the following works.
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In the following example, you would replace "<filename>bsp</filename>" and
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"<filename>_bsp</filename>" with the actual name
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of the BSP (i.e. <filename><bsp_name></filename> from the example template).
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</para>
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<para>
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<literallayout class='monospaced'>
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# We have a conf and classes directory, add to BBPATH
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BBPATH := "${BBPATH}:${LAYERDIR}"
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# We have a recipes directory, add to BBFILES
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BBFILES := "${BBFILES} ${LAYERDIR}/recipes/*/*.bb \
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${LAYERDIR}/recipes/*/*.bbappend"
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BBFILE_COLLECTIONS += "bsp"
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BBFILE_PATTERN_bsp := "^${LAYERDIR}/"
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BBFILE_PRIORITY_bsp = "6"
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</literallayout>
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</para>
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<para>
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To illustrate the string substitutions, here are the last three statements from the Crown
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Bay <filename>conf/layer.conf</filename> file:
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<literallayout class='monospaced'>
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BBFILE_COLLECTIONS += "crownbay"
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BBFILE_PATTERN_crownbay := "^${LAYERDIR}/"
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BBFILE_PRIORITY_crownbay = "6"
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</literallayout>
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</para>
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<para>
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This file simply makes BitBake aware of the recipes and configuration directories.
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The file must exist so that the Yocto Project build system can recognize the BSP.
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</para>
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</section>
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<section id="bsp-filelayout-machine">
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<title>Hardware Configuration Options</title>
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<para>
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You can find these files in the BSP Layer at:
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<literallayout class='monospaced'>
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meta-<bsp_name>/conf/machine/*.conf
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</literallayout>
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</para>
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<para>
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The machine files bind together all the information contained elsewhere
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in the BSP into a format that the Yocto Project build system can understand.
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If the BSP supports multiple machines, multiple machine configuration files
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can be present.
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These filenames correspond to the values to which users have set the
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<ulink url='http://www.yoctoproject.org/docs/latest/poky-ref-manual/poky-ref-manual.html#var-MACHINE'><filename>MACHINE</filename></ulink> variable.
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</para>
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<para>
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These files define things such as the kernel package to use
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(<ulink url='http://www.yoctoproject.org/docs/latest/poky-ref-manual/poky-ref-manual.html#var-PREFERRED_PROVIDER'><filename>PREFERRED_PROVIDER</filename></ulink>
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of virtual/kernel), the hardware drivers to
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include in different types of images, any special software components
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that are needed, any bootloader information, and also any special image
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format requirements.
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</para>
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<para>
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Each BSP Layer requires at least one machine file.
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However, you can supply more than one file.
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For example, in the Crown Bay BSP shown earlier in this section, the
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<filename>conf/machine</filename> directory contains two configuration files:
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<filename>crownbay.conf</filename> and <filename>crownbay-noemgd.conf</filename>.
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The <filename>crownbay.conf</filename> file is used for the Crown Bay BSP
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that supports the <trademark class='registered'>Intel</trademark> Embedded
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Media and Graphics Driver (<trademark class='registered'>Intel</trademark>
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EMGD), while the <filename>crownbay-noemgd.conf</filename> file is used for the
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Crown Bay BSP that does not support the <trademark class='registered'>Intel</trademark>
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EMGD.
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</para>
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<para>
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This <filename>crownbay.conf</filename> file could also include
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a hardware "tuning" file that is commonly used to
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define the package architecture and specify
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optimization flags, which are carefully chosen to give best
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performance on a given processor.
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</para>
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<para>
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Tuning files are found in the <filename>meta/conf/machine/include</filename>
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directory of the
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<ulink url='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#yocto-project-files'>Yocto Project Files</ulink>.
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Tuning files can also reside in the BSP Layer itself.
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For example, the <filename>ia32-base.inc</filename> file resides in the
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<filename>meta-intel</filename> BSP Layer in <filename>conf/machine/include</filename>.
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</para>
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<para>
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To use an include file, you simply include them in the machine configuration file.
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For example, the Crown Bay BSP <filename>crownbay.conf</filename> has the
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following statements:
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<literallayout class='monospaced'>
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include conf/machine/include/tune-atom.inc
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include conf/machine/include/ia32-base.inc
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</literallayout>
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</para>
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</section>
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<section id='bsp-filelayout-misc-recipes'>
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<title>Miscellaneous Recipe Files</title>
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<para>
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You can find these files in the BSP Layer at:
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<literallayout class='monospaced'>
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meta-<bsp_name>/recipes-bsp/*
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</literallayout>
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</para>
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<para>
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This optional directory contains miscellaneous recipe files for the BSP.
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Most notably would be the formfactor files.
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For example, in the Crown Bay BSP there is the
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<filename>formfactor_0.0.bbappend</filename> file, which is an append file used
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to augment the recipe that starts the build.
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Furthermore, there are machine-specific settings used during the build that are
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defined by the <filename>machconfig</filename> files.
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In the Crown Bay example, two <filename>machconfig</filename> files exist:
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one that supports the
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<trademark class='registered'>Intel</trademark> Embedded
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Media and Graphics Driver (<trademark class='registered'>Intel</trademark>
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EMGD) and one that does not:
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<literallayout class='monospaced'>
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meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig
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meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/machconfig
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meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend
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</literallayout>
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</para>
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<note><para>
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If a BSP does not have a formfactor entry, defaults are established according to
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the formfactor configuration file that is installed by the main
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formfactor recipe
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<filename>meta/recipes-bsp/formfactor/formfactor_0.0.bb</filename>,
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which is found in the
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<ulink url='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#yocto-project-files'>Yocto Project Files</ulink>.
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</para></note>
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</section>
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<section id='bsp-filelayout-core-recipes'>
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<title>Core Recipe Files</title>
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<para>
|
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You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/recipes-core/*
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
This directory contains recipe files that are almost always necessary to build a
|
|
useful, working Linux image.
|
|
Thus, the term "core" is used to group these recipes.
|
|
For example, in the Crown Bay BSP there is the
|
|
<filename>task-core-tools-profile.bbappend</filename> file, which is an append file used
|
|
to recommend that the
|
|
<ulink url='http://sourceware.org/systemtap/wiki'>SystemTap</ulink>
|
|
package be included as a package when the image is built.
|
|
</para>
|
|
</section>
|
|
|
|
<section id='bsp-filelayout-recipes-graphics'>
|
|
<title>Display Support Files</title>
|
|
<para>
|
|
You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/recipes-graphics/*
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
This optional directory contains recipes for the BSP if it has
|
|
special requirements for graphics support.
|
|
All files that are needed for the BSP to support a display are kept here.
|
|
For example, the Crown Bay BSP contains two versions of the
|
|
<filename>xorg.conf</filename> file.
|
|
The version in <filename>crownbay</filename> builds a BSP that supports the
|
|
<trademark class='registered'>Intel</trademark> Embedded Media Graphics Driver (EMGD),
|
|
while the version in <filename>crownbay-noemgd</filename> builds
|
|
a BSP that supports Video Electronics Standards Association (VESA) graphics only:
|
|
<literallayout class='monospaced'>
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xorg.conf
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/xorg.conf
|
|
</literallayout>
|
|
</para>
|
|
</section>
|
|
|
|
<section id='bsp-filelayout-kernel'>
|
|
<title>Linux Kernel Configuration</title>
|
|
<para>
|
|
You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/recipes-kernel/linux/linux-yocto_*.bbappend
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
These files append your specific changes to the kernel you are using.
|
|
</para>
|
|
<para>
|
|
For your BSP, you typically want to use an existing Yocto Project kernel found in the
|
|
<ulink url='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#yocto-project-files'>Yocto
|
|
Project Files</ulink> at <filename>meta/recipes-kernel/linux</filename>.
|
|
You can append your specific changes to the kernel recipe by using a
|
|
similarly named append file, which is located in BSP Layer (e.g.
|
|
the <filename>meta-<bsp_name>/recipes-kernel/linux</filename> directory).
|
|
</para>
|
|
<para>
|
|
Suppose the BSP uses the <filename>linux-yocto_3.0.bb</filename> kernel,
|
|
which is the preferred kernel to use for developing a new BSP using the Yocto Project.
|
|
In other words, you have selected the kernel in your
|
|
<filename><bsp_name>.conf</filename> file by adding the following statements:
|
|
<literallayout class='monospaced'>
|
|
PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
|
|
PREFERRED_VERSION_linux-yocto = "3.0%"
|
|
</literallayout>
|
|
You would use the <filename>linux-yocto_3.0.bbappend</filename> file to append
|
|
specific BSP settings to the kernel, thus configuring the kernel for your particular BSP.
|
|
</para>
|
|
<para>
|
|
As an example, look at the existing Crown Bay BSP.
|
|
The append file used is:
|
|
<literallayout class='monospaced'>
|
|
meta-crownbay/recipes-kernel/linux/linux-yocto_3.0.bbappend
|
|
</literallayout>
|
|
The following listing shows the file.
|
|
Be aware that the actual commit ID strings in this example listing might be different
|
|
than the actual strings in the file from the <filename>meta-intel</filename>
|
|
Git source repository.
|
|
<literallayout class='monospaced'>
|
|
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
|
|
|
|
COMPATIBLE_MACHINE_crownbay = "crownbay"
|
|
KMACHINE_crownbay = "yocto/standard/crownbay"
|
|
KERNEL_FEATURES_append_crownbay += " cfg/smp.scc"
|
|
|
|
COMPATIBLE_MACHINE_crownbay-noemgd = "crownbay-noemgd"
|
|
KMACHINE_crownbay-noemgd = "yocto/standard/crownbay"
|
|
KERNEL_FEATURES_append_crownbay-noemgd += " cfg/smp.scc"
|
|
|
|
SRCREV_machine_pn-linux-yocto_crownbay ?= "63c65842a3a74e4bd3128004ac29b5639f16433f"
|
|
SRCREV_meta_pn-linux-yocto_crownbay ?= "59314a3523e360796419d76d78c6f7d8c5ef2593"
|
|
|
|
SRCREV_machine_pn-linux-yocto_crownbay-noemgd ?= "63c65842a3a74e4bd3128004ac29b5639f16433f"
|
|
SRCREV_meta_pn-linux-yocto_crownbay-noemgd ?= "59314a3523e360796419d76d78c6f7d8c5ef2593"
|
|
</literallayout>
|
|
This append file contains statements used to support the Crown Bay BSP for both
|
|
<trademark class='registered'>Intel</trademark> EMGD and the VESA graphics.
|
|
The build process, in this case, recognizes and uses only the statements that
|
|
apply to the defined machine name - <filename>crownbay</filename> in this case.
|
|
So, the applicable statements in the <filename>linux-yocto_3.0.bbappend</filename>
|
|
file are follows:
|
|
<literallayout class='monospaced'>
|
|
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
|
|
|
|
COMPATIBLE_MACHINE_crownbay = "crownbay"
|
|
KMACHINE_crownbay = "yocto/standard/crownbay"
|
|
KERNEL_FEATURES_append_crownbay += " cfg/smp.scc"
|
|
|
|
SRCREV_machine_pn-linux-yocto_crownbay ?= "63c65842a3a74e4bd3128004ac29b5639f16433f"
|
|
SRCREV_meta_pn-linux-yocto_crownbay ?= "59314a3523e360796419d76d78c6f7d8c5ef2593"
|
|
</literallayout>
|
|
The append file defines <filename>crownbay</filename> as the compatible machine,
|
|
defines the <filename>KMACHINE</filename>, points to some configuration fragments
|
|
to use by setting the <filename>KERNEL_FEATURES</filename> variable, and then points
|
|
to the specific commits in the Yocto Project Files Git repository and the
|
|
<filename>meta</filename> Git repository branches to identify the exact kernel needed
|
|
to build the Crown Bay BSP.
|
|
</para>
|
|
<para>
|
|
One thing missing in this particular BSP, which you will typically need when
|
|
developing a BSP, is the kernel configuration file (<filename>.config</filename>) for your BSP.
|
|
When developing a BSP, you probably have a kernel configuration file or a set of kernel
|
|
configuration files that, when taken together, define the kernel configuration for your BSP.
|
|
You can accomplish this definition by putting the configurations in a file or a set of files
|
|
inside a directory located at the same level as your append file and having the same name
|
|
as the kernel.
|
|
With all these conditions met simply reference those files in a
|
|
<filename>SRC_URI</filename> statement in the append file.
|
|
</para>
|
|
<para>
|
|
For example, suppose you had a set of configuration options in a file called
|
|
<filename>defconfig</filename>.
|
|
If you put that file inside a directory named
|
|
<filename>/linux-yocto</filename> and then added
|
|
a <filename>SRC_URI</filename> statement such as the following to the append file,
|
|
those configuration
|
|
options will be picked up and applied when the kernel is built.
|
|
<literallayout class='monospaced'>
|
|
SRC_URI += "file://defconfig"
|
|
</literallayout>
|
|
</para>
|
|
<para>
|
|
As mentioned earlier, you can group related configurations into multiple files and
|
|
name them all in the <filename>SRC_URI</filename> statement as well.
|
|
For example, you could group separate configurations specifically for Ethernet and graphics
|
|
into their own files and add those by using a <filename>SRC_URI</filename> statement like the
|
|
following in your append file:
|
|
<literallayout class='monospaced'>
|
|
SRC_URI += "file://defconfig \
|
|
file://eth.cfg \
|
|
file://gfx.cfg"
|
|
</literallayout>
|
|
</para>
|
|
<para>
|
|
The <filename>FILESEXTRAPATHS</filename> variable is in boilerplate form here
|
|
in order to make it easy to do that.
|
|
It basically allows those configuration files to be found by the build process.
|
|
</para>
|
|
<note>
|
|
<para>
|
|
Other methods exist to accomplish grouping and defining configuration options.
|
|
For example, you could directly add configuration options to the Yocto kernel
|
|
<filename>meta</filename> branch for your BSP.
|
|
The configuration options will likely end up in that location anyway if the BSP gets
|
|
added to the Yocto Project.
|
|
For an example showing how to change the BSP configuration, see the
|
|
"<ulink url='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#changing-the-bsp-configuration'>Changing the BSP Configuration</ulink>" section
|
|
in the Yocto Project Development Manual.</para>
|
|
<para>
|
|
In general, however, the Yocto Project maintainers take care of moving the
|
|
<filename>SRC_URI</filename>-specified
|
|
configuration options to the <filename>meta</filename> branch.
|
|
Not only is it easier for BSP developers to not have to worry about putting those
|
|
configurations in the branch, but having the maintainers do it allows them to apply
|
|
'global' knowledge about the kinds of common configuration options multiple BSPs in
|
|
the tree are typically using.
|
|
This allows for promotion of common configurations into common features.</para>
|
|
</note>
|
|
</section>
|
|
</section>
|
|
|
|
<section id='bsp-click-through-licensing'>
|
|
<title>BSP 'Click-Through' Licensing Procedure</title>
|
|
|
|
<note> This section describes how
|
|
click-through licensing is expected to work.
|
|
Currently, this functionality is not yet implemented.
|
|
</note>
|
|
|
|
<para>
|
|
In some cases, a BSP contains separately licensed IP
|
|
(Intellectual Property) for a component that imposes
|
|
upon the user a requirement to accept the terms of a
|
|
'click-through' license.
|
|
Once the license is accepted the
|
|
Yocto Project build system can then build and include the
|
|
corresponding component in the final BSP image.
|
|
Some affected components might be essential to the normal
|
|
functioning of the system and have no 'free' replacement
|
|
(i.e. the resulting system would be non-functional
|
|
without them).
|
|
On the other hand, other components might be simply
|
|
'good-to-have' or purely elective, or if essential
|
|
nonetheless have a 'free' (possibly less-capable)
|
|
version that could be used as a in the BSP recipe.
|
|
</para>
|
|
|
|
<para>
|
|
For cases where you can substitute something and still maintain functionality,
|
|
the Yocto Project website's
|
|
<ulink url='http://www.yoctoproject.org/download/all?keys=&download_type=1&download_version='>BSP Download Page</ulink>
|
|
makes available 'de-featured' BSPs that are completely free of any IP encumbrances.
|
|
For these cases you can use the substitution directly and without any further licensing
|
|
requirements.
|
|
If present, these fully 'de-featured' BSPs are named appropriately different
|
|
as compared to the names of the respective encumbered BSPs.
|
|
If available, these substitutions are the simplest and most preferred options.
|
|
This, of course, assumes the resulting functionality meets requirements.
|
|
</para>
|
|
|
|
<para>
|
|
If however, a non-encumbered version is unavailable or the 'free' version
|
|
would provide unsuitable functionality or quality, you can use
|
|
an encumbered version.
|
|
</para>
|
|
|
|
<para>
|
|
Several methods exist within the Yocto Project build system to satisfy the licensing
|
|
requirements for an encumbered BSP.
|
|
The following list describes them in preferential order:
|
|
</para>
|
|
|
|
<orderedlist>
|
|
<listitem>
|
|
|
|
<para>
|
|
Get a license key (or keys) for the encumbered BSP by visiting
|
|
a website and providing the name of the BSP and your email address
|
|
through a web form.
|
|
</para>
|
|
|
|
<para>
|
|
After agreeing to any applicable license terms, the
|
|
BSP key(s) will be immediately sent to the address
|
|
you gave and you can use them by specifying BSPKEY_<keydomain>
|
|
environment variables when building the image:
|
|
</para>
|
|
|
|
<literallayout class='monospaced'>
|
|
$ BSPKEY_<keydomain>=<key> bitbake core-image-sato
|
|
</literallayout>
|
|
|
|
<para>
|
|
These steps allow the encumbered image to be built
|
|
with no change at all to the normal build process.
|
|
</para>
|
|
|
|
<para>
|
|
Equivalently and probably more conveniently, a line
|
|
for each key can instead be put into the user's
|
|
<filename>local.conf</filename> file found in the Yocto Project file's
|
|
build directory.
|
|
</para>
|
|
|
|
<para>
|
|
The <keydomain> component of the
|
|
BSPKEY_<keydomain> is required because there
|
|
might be multiple licenses in effect for a given BSP.
|
|
In such cases, a given <keydomain> corresponds to
|
|
a particular license. In order for an encumbered
|
|
BSP that encompasses multiple key domains to be built
|
|
successfully, a <keydomain> entry for each
|
|
applicable license must be present in <filename>local.conf</filename> or
|
|
supplied on the command-line.
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
Do nothing - build as you normally would.
|
|
When a license is needed the build will stop and prompt you with instructions.
|
|
Follow the license prompts that originate from the
|
|
encumbered BSP.
|
|
These prompts usually take the form of instructions
|
|
needed to manually fetch the encumbered package(s)
|
|
and md5 sums into the required directory
|
|
(e.g. the <filename>yocto/build/downloads</filename>).
|
|
Once the manual package fetch has been
|
|
completed, restart the build to continue where
|
|
it left off.
|
|
During the build the prompt will not appear again since you have satisfied the
|
|
requirement.
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
Get a full-featured BSP recipe rather than a key.
|
|
You can do this by visiting the Yocto Project website's
|
|
<ulink url='http://www.yoctoproject.org/download'>Download</ulink> page and
|
|
clicking on "BSP Downloads".
|
|
BSP tarballs that have proprietary information can be downloaded after agreeing
|
|
to licensing requirements as part of the download process.
|
|
Obtaining the code this way allows you to build an encumbered image with
|
|
no changes at all as compared to the normal build.
|
|
</para>
|
|
</listitem>
|
|
</orderedlist>
|
|
<para>
|
|
Note that the third method is also the only option available
|
|
when downloading pre-compiled images generated from non-free BSPs.
|
|
Those images are likewise available at from the Yocto Project website.
|
|
</para>
|
|
</section>
|
|
|
|
</chapter>
|