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diff --git a/import-layers/yocto-poky/documentation/bsp-guide/bsp.xml b/import-layers/yocto-poky/documentation/bsp-guide/bsp.xml new file mode 100644 index 000000000..b0562c7d4 --- /dev/null +++ b/import-layers/yocto-poky/documentation/bsp-guide/bsp.xml @@ -0,0 +1,1697 @@ +<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" +"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" +[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] > + +<chapter id='bsp'> + + <title>Board Support Packages (BSP) - Developer's Guide</title> + + <para> + A Board Support Package (BSP) is a collection of information that + defines how to support a particular hardware device, set of devices, or + hardware platform. + The BSP includes information about the hardware features + present on the device and kernel configuration information along with any + additional hardware drivers required. + The BSP also lists any additional software + components required in addition to a generic Linux software stack for both + essential and optional platform features. + </para> + + <para> + This guide presents information about BSP Layers, defines a structure for components + so that BSPs follow a commonly understood layout, discusses how to customize + a recipe for a BSP, addresses BSP licensing, and provides information that + shows you how to create and manage a + <link linkend='bsp-layers'>BSP Layer</link> using two Yocto Project + <link linkend='using-the-yocto-projects-bsp-tools'>BSP Tools</link>. + </para> + + <section id='bsp-layers'> + <title>BSP Layers</title> + + <para> + A BSP consists of a file structure inside a base directory. + Collectively, you can think of the base directory, its file structure, + and the contents as a BSP Layer. + Although not a strict requirement, layers in the Yocto Project use the + following well-established naming convention: + <literallayout class='monospaced'> + meta-<replaceable>bsp_name</replaceable> + </literallayout> + The string "meta-" is prepended to the machine or platform name, which is + <replaceable>bsp_name</replaceable> in the above form. + <note><title>Tip</title> + Because the BSP layer naming convention is well-established, + it is advisable to follow it when creating layers. + Technically speaking, a BSP layer name does not need to + start with <filename>meta-</filename>. + However, you might run into situations where obscure + scripts assume this convention. + </note> + </para> + + <para> + To help understand the BSP layer concept, consider the BSPs that the + Yocto Project supports and provides with each release. + You can see the layers in the + <ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-repositories'>Yocto Project Source Repositories</ulink> + through a web interface at + <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi'></ulink>. + If you go to that interface, you will find near the bottom of the list + under "Yocto Metadata Layers" several BSP layers all of which are + supported by the Yocto Project (e.g. <filename>meta-raspberrypi</filename> and + <filename>meta-intel</filename>). + Each of these layers is a repository unto itself and clicking on a + layer reveals information that includes two links from which you can choose + to set up a clone of the layer's repository on your local host system. + Here is an example that clones the Raspberry Pi BSP layer: + <literallayout class='monospaced'> + $ git clone git://git.yoctoproject.org/meta-raspberrypi + </literallayout> + </para> + + <para> + In addition to BSP layers near the bottom of that referenced + Yocto Project Source Repository, the + <filename>meta-yocto-bsp</filename> layer is part of the + shipped <filename>poky</filename> repository. + The <filename>meta-yocto-bsp</filename> layer maintains several + BSPs such as the Beaglebone, EdgeRouter, and generic versions of + both 32 and 64-bit IA machines. + </para> + + <para> + For information on the BSP development workflow, see the + "<ulink url='&YOCTO_DOCS_DEV_URL;#developing-a-board-support-package-bsp'>Developing a Board Support Package (BSP)</ulink>" + section in the Yocto Project Development Manual. + For more information on how to set up a local copy of source files + from a Git repository, see the + "<ulink url='&YOCTO_DOCS_DEV_URL;#getting-setup'>Getting Set Up</ulink>" + section also in the Yocto Project Development Manual. + </para> + + <para> + The layer's base directory + (<filename>meta-<replaceable>bsp_name</replaceable></filename>) + is the root of the BSP Layer. + This root is what you add to the + <ulink url='&YOCTO_DOCS_REF_URL;#var-BBLAYERS'><filename>BBLAYERS</filename></ulink> + variable in the <filename>conf/bblayers.conf</filename> file found in the + <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>, + which is established after you run one of the OpenEmbedded build environment + setup scripts (i.e. + <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink> + and + <ulink url='&YOCTO_DOCS_REF_URL;#structure-memres-core-script'><filename>oe-init-build-env-memres</filename></ulink>). + Adding the root allows the OpenEmbedded build system to recognize the BSP + definition and from it build an image. + Here is an example: + <literallayout class='monospaced'> + BBLAYERS ?= " \ + /usr/local/src/yocto/meta \ + /usr/local/src/yocto/meta-poky \ + /usr/local/src/yocto/meta-yocto-bsp \ + /usr/local/src/yocto/meta-mylayer \ + " + </literallayout> + </para> + + <para> + Some BSPs require additional layers on + top of the BSP's root layer in order to be functional. + For these cases, you also need to add those layers to the + <filename>BBLAYERS</filename> variable in order to build the BSP. + You must also specify in the "Dependencies" section of the BSP's + <filename>README</filename> file any requirements for additional + layers and, preferably, any + build instructions that might be contained elsewhere + in the <filename>README</filename> file. + </para> + + <para> + Some layers function as a layer to hold other BSP layers. + An example of this type of layer is the <filename>meta-intel</filename> layer, + which contains a number of individual BSP sub-layers, as well as a directory + named <filename>common/</filename> full of common content across those layers. + Another example is the <filename>meta-yocto-bsp</filename> layer mentioned + earlier. + </para> + + <para> + For more detailed information on layers, see the + "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>" + section of the Yocto Project Development Manual. + </para> + </section> + + <section id="bsp-filelayout"> + <title>Example Filesystem Layout</title> + + <para> + Defining a common BSP directory structure allows end-users to understand and + become familiar with that structure. + A common format also encourages standardization of software support of hardware. + </para> + + <para> + The proposed form does have elements that are specific to the + OpenEmbedded build system. + It is intended that this information can be + used by other build systems besides the OpenEmbedded build system + and that it will be simple + to extract information and convert it to other formats if required. + The OpenEmbedded build system, through its standard layers mechanism, can directly + accept the format described as a layer. + The BSP captures all + the hardware-specific details in one place in a standard format, which is + useful for any person wishing to use the hardware platform regardless of + the build system they are using. + </para> + + <para> + The BSP specification does not include a build system or other tools - + it is concerned with the hardware-specific components only. + At the end-distribution point, you can ship the BSP combined with a build system + and other tools. + However, it is important to maintain the distinction that these + are separate components that happen to be combined in certain end products. + </para> + + <para> + Before looking at the common form for the file structure inside a BSP Layer, + you should be aware that some requirements do exist in order for a BSP to + be considered compliant with the Yocto Project. + For that list of requirements, see the + "<link linkend='released-bsp-requirements'>Released BSP Requirements</link>" + section. + </para> + + <para> + Below is the common form for the file structure inside a BSP Layer. + While you can use this basic form for the standard, realize that the actual structures + for specific BSPs could differ. + + <literallayout class='monospaced'> + meta-<replaceable>bsp_name</replaceable>/ + meta-<replaceable>bsp_name</replaceable>/<replaceable>bsp_license_file</replaceable> + meta-<replaceable>bsp_name</replaceable>/README + meta-<replaceable>bsp_name</replaceable>/README.sources + meta-<replaceable>bsp_name</replaceable>/binary/<replaceable>bootable_images</replaceable> + meta-<replaceable>bsp_name</replaceable>/conf/layer.conf + meta-<replaceable>bsp_name</replaceable>/conf/machine/*.conf + meta-<replaceable>bsp_name</replaceable>/recipes-bsp/* + meta-<replaceable>bsp_name</replaceable>/recipes-core/* + meta-<replaceable>bsp_name</replaceable>/recipes-graphics/* + meta-<replaceable>bsp_name</replaceable>/recipes-kernel/linux/linux-yocto_<replaceable>kernel_rev</replaceable>.bbappend + </literallayout> + </para> + + <para> + Below is an example of the Raspberry Pi BSP: + + <literallayout class='monospaced'> + meta-raspberrypi/COPYING.MIT + meta-raspberrypi/README + meta-raspberrypi/classes + meta-raspberrypi/classes/linux-raspberrypi-base.bbclass + meta-raspberrypi/classes/sdcard_image-rpi.bbclass + meta-raspberrypi/conf/ + meta-raspberrypi/conf/layer.conf + meta-raspberrypi/conf/machine/ + meta-raspberrypi/conf/machine/raspberrypi.conf + meta-raspberrypi/conf/machine/raspberrypi0.conf + meta-raspberrypi/conf/machine/raspberrypi2.conf + meta-raspberrypi/conf/machine/raspberrypi3.conf + meta-raspberrypi/conf/machine/include + meta-raspberrypi/conf/machine/include/rpi-base.inc + meta-raspberrypi/conf/machine/include/rpi-default-providers.inc + meta-raspberrypi/conf/machine/include/rpi-default-settings.inc + meta-raspberrypi/conf/machine/include/rpi-default-versions.inc + meta-raspberrypi/conf/machine/include/rpi-tune-arm1176jzf-s.inc + meta-raspberrypi/files + meta-raspberrypi/files/custom-licenses + meta-raspberrypi/files/custom-licenses/Broadcom + meta-raspberrypi/recipes-bsp + meta-raspberrypi/recipes-bsp/bootfiles + meta-raspberrypi/recipes-bsp/bootfiles/bcm2835-bootfiles.bb + meta-raspberrypi/recipes-bsp/bootfiles/rpi-config_git.bb + meta-raspberrypi/recipes-bsp/common + meta-raspberrypi/recipes-bsp/common/firmware.inc + meta-raspberrypi/recipes-bsp/formfactor_00.bbappend + meta-raspberrypi/recipes-bsp/formfactor/raspberrypi/machconfig + meta-raspberrypi/recipes-bsp/rpi-mkimage_git.bb + meta-raspberrypi/recipes-bsp/rpi-mkimage/License + meta-raspberrypi/recipes-bsp/rpi-mkimage/open-files-relative-to-script.patch + meta-raspberrypi/recipes-bsp/u-boot/u-boot-rpi_git.bb + meta-raspberrypi/recipes-core + meta-raspberrypi/recipes-core/images + meta-raspberrypi/recipes-core/images/rpi-basic-image.bb + meta-raspberrypi/recipes-core/images/rpi-hwup-image.bb + meta-raspberrypi/recipes-core/images/rpi-test-image.bb + meta-raspberrypi/recipes-core/packagegroups + meta-raspberrypi/recipes-core/packagegroups/packagegroup-rpi-test.bb + meta-raspberrypi/recipes-core/psplash + meta-raspberrypi/recipes-core/psplash/files + meta-raspberrypi/recipes-core/psplash/psplash_git.bbappend + meta-raspberrypi/recipes-core/psplash/files/psplash-raspberrypi-img.h + meta-raspberrypi/recipes-devtools + meta-raspberrypi/recipes-devtools/bcm2835 + meta-raspberrypi/recipes-devtools/bcm2835/bcm2835_1.46.bb + meta-raspberrypi/recipes-devtools/pi-blaster + meta-raspberrypi/recipes-devtools/pi-blaster/files + meta-raspberrypi/recipes-devtools/pi-blaster/*.patch + meta-raspberrypi/recipes-devtools/pi-blaster/pi-blaster.inc + meta-raspberrypi/recipes-devtools/pi-blaster/pi-blaster_git.bb + meta-raspberrypi/recipes-devtools/python + meta-raspberrypi/recipes-devtools/python/python-rtimu + meta-raspberrypi/recipes-devtools/python/python-rtimu/*.patch + meta-raspberrypi/recipes-devtools/python/python-rtimu_git.bb + meta-raspberrypi/recipes-devtools/python/python-sense-hat_2.1.0.bb + meta-raspberrypi/recipes-devtools/python/rpi-gpio + meta-raspberrypi/recipes-devtools/python/rpi-gpio/*.patch + meta-raspberrypi/recipes-devtools/python/rpi-gpio_0.6.1.bb + meta-raspberrypi/recipes-devtools/python/rpio + meta-raspberrypi/recipes-devtools/python/rpio/*.patch + meta-raspberrypi/recipes-devtools/python/rpio_0.10.0.bb + meta-raspberrypi/recipes-devtools/wiringPi + meta-raspberrypi/recipes-devtools/wiringPi/files + meta-raspberrypi/recipes-devtools/wiringPi/files/*.patch + meta-raspberrypi/recipes-devtools/wiringPi/wiringpi + meta-raspberrypi/recipes-devtools/wiringPi/wiringpi/*.patch + meta-raspberrypi/recipes-devtools/wiringPi/wiringpi_git.bb + meta-raspberrypi/recipes-graphics + meta-raspberrypi/recipes-graphics/eglinfo + meta-raspberrypi/recipes-graphics/eglinfo/eglinfo-fb_%.bbappend + meta-raspberrypi/recipes-graphics/eglinfo/eglinfo-x11_%.bbappend + meta-raspberrypi/recipes-graphics/userland + meta-raspberrypi/recipes-graphics/userland/userland + meta-raspberrypi/recipes-graphics/userland/userland/*.patch + meta-raspberrypi/recipes-graphics/userland/userland_git.bb + meta-raspberrypi/recipes-graphics/vc-graphics + meta-raspberrypi/recipes-graphics/vc-graphics/files + meta-raspberrypi/recipes-graphics/vc-graphics/files/egl.pc + meta-raspberrypi/recipes-graphics/vc-graphics/files/vchiq.sh + meta-raspberrypi/recipes-graphics/vc-graphics/vc-graphics-hardfp.bb + meta-raspberrypi/recipes-graphics/vc-graphics/vc-graphics.bb + meta-raspberrypi/recipes-graphics/vc-graphics/vc-graphics.inc + meta-raspberrypi/recipes-graphics/wayland + meta-raspberrypi/recipes-graphics/wayland/weston_%.bbappend + meta-raspberrypi/recipes-graphics/weston + meta-raspberrypi/recipes-graphics/weston/weston_%.bbappend + meta-raspberrypi/recipes-graphics/xorg-xserver + meta-raspberrypi/recipes-graphics/xorg-xserver/xserver-xf86-config + meta-raspberrypi/recipes-graphics/xorg-xserver/xserver-xf86-config/rpi + meta-raspberrypi/recipes-graphics/xorg-xserver/xserver-xf86-config/rpi/xorg.conf + meta-raspberrypi/recipes-graphics/xorg-xserver/xserver-xf86-config/rpi/xorg.conf.d + meta-raspberrypi/recipes-graphics/xorg-xserver/xserver-xf86-config/rpi/xorg.conf.d/10-evdev.conf + meta-raspberrypi/recipes-graphics/xorg-xserver/xserver-xf86-config/rpi/xorg.conf.d/99-pitft.conf + meta-raspberrypi/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend + meta-raspberrypi/recipes-kernel + meta-raspberrypi/recipes-kernel/linux-firmware + meta-raspberrypi/recipes-kernel/linux-firmware/linux-firmware + meta-raspberrypi/recipes-kernel/linux-firmware/linux-firmware/LICENSE.broadcom_brcm80211 + meta-raspberrypi/recipes-kernel/linux-firmware/linux-firmware/brcmfmac43430-sdio.bin + meta-raspberrypi/recipes-kernel/linux-firmware/linux-firmware/brcmfmac43430-sdio.txt + meta-raspberrypi/recipes-kernel/linux-firmware/linux-firmware_git.bbappend + meta-raspberrypi/recipes-kernel/linux + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi-3.14 + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi-3.14/*.patch + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi-3.18 + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi-3.18/*.patch + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi-4.1 + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi-4.1/*.patch + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi.inc + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi/defconfig + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi_3.14.bb + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi_3.18.bb + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi_4.1.bb + meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi_4.4.bb + meta-raspberrypi/recipes-kernel/linux/linux.inc + meta-raspberrypi/recipes-multimedia + meta-raspberrypi/recipes-multimedia/gstreamer + meta-raspberrypi/recipes-multimedia/gstreamer/gstreamer1.0-omx + meta-raspberrypi/recipes-multimedia/gstreamer/gstreamer1.0-omx/*.patch + meta-raspberrypi/recipes-multimedia/gstreamer/gstreamer1.0-omx_%.bbappend + meta-raspberrypi/recipes-multimedia/gstreamer/gstreamer1.0-plugins-bad_%.bbappend + meta-raspberrypi/recipes-multimedia/omxplayer + meta-raspberrypi/recipes-multimedia/omxplayer/omxplayer + meta-raspberrypi/recipes-multimedia/omxplayer/omxplayer/*.patch + meta-raspberrypi/recipes-multimedia/omxplayer/omxplayer_git.bb + meta-raspberrypi/scripts + meta-raspberrypi/scripts/lib + meta-raspberrypi/scripts/lib/image + meta-raspberrypi/scripts/lib/image/canned-wks + meta-raspberrypi/scripts/lib/image/canned-wks/sdimage-raspberrypi.wks + </literallayout> + </para> + + <para> + The following sections describe each part of the proposed BSP format. + </para> + + <section id="bsp-filelayout-license"> + <title>License Files</title> + + <para> + You can find these files in the BSP Layer at: + <literallayout class='monospaced'> + meta-<replaceable>bsp_name</replaceable>/<replaceable>bsp_license_file</replaceable> + </literallayout> + </para> + + <para> + These optional files satisfy licensing requirements for the BSP. + The type or types of files here can vary depending on the licensing requirements. + For example, in the Raspberry Pi BSP all licensing requirements are handled with the + <filename>COPYING.MIT</filename> file. + </para> + + <para> + Licensing files can be MIT, BSD, GPLv*, and so forth. + These files are recommended for the BSP but are optional and totally up to the BSP developer. + </para> + </section> + + <section id="bsp-filelayout-readme"> + <title>README File</title> + <para> + You can find this file in the BSP Layer at: + <literallayout class='monospaced'> + meta-<replaceable>bsp_name</replaceable>/README + </literallayout> + </para> + + <para> + This file provides information on how to boot the live images that are optionally + included in the <filename>binary/</filename> directory. + The <filename>README</filename> file also provides special information needed for + building the image. + </para> + + <para> + At a minimum, the <filename>README</filename> file must + contain a list of dependencies, such as the names of + any other layers on which the BSP depends and the name of + the BSP maintainer with his or her contact information. + </para> + </section> + + <section id="bsp-filelayout-readme-sources"> + <title>README.sources File</title> + <para> + You can find this file in the BSP Layer at: + <literallayout class='monospaced'> + meta-<replaceable>bsp_name</replaceable>/README.sources + </literallayout> + </para> + + <para> + This file provides information on where to locate the BSP + source files used to build the images (if any) that reside in + <filename>meta-<replaceable>bsp_name</replaceable>/binary</filename>. + Images in the <filename>binary</filename> would be images + released with the BSP. + The information in the <filename>README.sources</filename> + file also helps you find the + <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink> + used to generate the images that ship with the BSP. + <note> + If the BSP's <filename>binary</filename> directory is + missing or the directory has no images, an existing + <filename>README.sources</filename> file is + meaningless. + </note> + </para> + </section> + + <section id="bsp-filelayout-binary"> + <title>Pre-built User Binaries</title> + <para> + You can find these files in the BSP Layer at: + <literallayout class='monospaced'> + meta-<replaceable>bsp_name</replaceable>/binary/<replaceable>bootable_images</replaceable> + </literallayout> + </para> + + <para> + This optional area contains useful pre-built kernels and + user-space filesystem images released with the BSP that are + appropriate to the target system. + This directory typically contains graphical (e.g. Sato) and + minimal live images when the BSP tarball has been created and + made available in the + <ulink url='&YOCTO_HOME_URL;'>Yocto Project</ulink> website. + You can use these kernels and images to get a system running + and quickly get started on development tasks. + </para> + + <para> + The exact types of binaries present are highly + hardware-dependent. + The <filename>README</filename> file should be present in the + BSP Layer and it will explain how to use the images with the + target hardware. + Additionally, the <filename>README.sources</filename> file + should be present to locate the sources used to build the + images and provide information on the Metadata. + </para> + </section> + + <section id='bsp-filelayout-layer'> + <title>Layer Configuration File</title> + <para> + You can find this file in the BSP Layer at: + <literallayout class='monospaced'> + meta-<replaceable>bsp_name</replaceable>/conf/layer.conf + </literallayout> + </para> + + <para> + The <filename>conf/layer.conf</filename> file identifies the file structure as a + layer, identifies the + contents of the layer, and contains information about how the build + system should use it. + Generally, a standard boilerplate file such as the following works. + In the following example, you would replace "<replaceable>bsp</replaceable>" and + "<replaceable>_bsp</replaceable>" with the actual name + of the BSP (i.e. <replaceable>bsp_name</replaceable> from the example template). + </para> + + <para> + <literallayout class='monospaced'> + # We have a conf and classes directory, add to BBPATH + BBPATH .= ":${LAYERDIR}" + + # We have a recipes directory, add to BBFILES + BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \ + ${LAYERDIR}/recipes-*/*/*.bbappend" + + BBFILE_COLLECTIONS += "<replaceable>bsp</replaceable>" + BBFILE_PATTERN_<replaceable>bsp</replaceable> = "^${LAYERDIR}/" + BBFILE_PRIORITY_<replaceable>bsp</replaceable> = "6" + + LAYERDEPENDS_<replaceable>bsp</replaceable> = "intel" + </literallayout> + </para> + + <para> + To illustrate the string substitutions, here are the corresponding statements + from the Raspberry Pi <filename>conf/layer.conf</filename> file: + <literallayout class='monospaced'> + # We have a conf and classes directory, append to BBPATH + BBPATH .= ":${LAYERDIR}" + + # We have a recipes directory containing .bb and .bbappend files, add to BBFILES + BBFILES += "${LAYERDIR}/recipes*/*/*.bb \ + ${LAYERDIR}/recipes*/*/*.bbappend" + + BBFILE_COLLECTIONS += "raspberrypi" + BBFILE_PATTERN_raspberrypi := "^${LAYERDIR}/" + BBFILE_PRIORITY_raspberrypi = "9" + + # Additional license directories. + LICENSE_PATH += "${LAYERDIR}/files/custom-licenses" + </literallayout> + </para> + + <para> + This file simply makes + <ulink url='&YOCTO_DOCS_DEV_URL;#bitbake-term'>BitBake</ulink> + aware of the recipes and configuration directories. + The file must exist so that the OpenEmbedded build system can recognize the BSP. + </para> + </section> + + <section id="bsp-filelayout-machine"> + <title>Hardware Configuration Options</title> + <para> + You can find these files in the BSP Layer at: + <literallayout class='monospaced'> + meta-<replaceable>bsp_name</replaceable>/conf/machine/*.conf + </literallayout> + </para> + + <para> + The machine files bind together all the information contained elsewhere + in the BSP into a format that the build system can understand. + If the BSP supports multiple machines, multiple machine configuration files + can be present. + These filenames correspond to the values to which users have set the + <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink> variable. + </para> + + <para> + These files define things such as the kernel package to use + (<ulink url='&YOCTO_DOCS_REF_URL;#var-PREFERRED_PROVIDER'><filename>PREFERRED_PROVIDER</filename></ulink> + of virtual/kernel), the hardware drivers to + include in different types of images, any special software components + that are needed, any bootloader information, and also any special image + format requirements. + </para> + + <para> + Each BSP Layer requires at least one machine file. + However, you can supply more than one file. + </para> + + <para> + This configuration file could also include a hardware "tuning" + file that is commonly used to define the package architecture + and specify optimization flags, which are carefully chosen + to give best performance on a given processor. + </para> + + <para> + Tuning files are found in the <filename>meta/conf/machine/include</filename> + directory within the + <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>. + For example, the <filename>ia32-base.inc</filename> file resides in the + <filename>meta/conf/machine/include</filename> directory. + </para> + + <para> + To use an include file, you simply include them in the + machine configuration file. + For example, the Raspberry Pi BSP + <filename>raspberrypi3.conf</filename> contains the + following statement: + <literallayout class='monospaced'> + include conf/machine/raspberrypi2.conf + </literallayout> + </para> + </section> + + <section id='bsp-filelayout-misc-recipes'> + <title>Miscellaneous BSP-Specific Recipe Files</title> + <para> + You can find these files in the BSP Layer at: + <literallayout class='monospaced'> + meta-<replaceable>bsp_name</replaceable>/recipes-bsp/* + </literallayout> + </para> + + <para> + This optional directory contains miscellaneous recipe files for + the BSP. + Most notably would be the formfactor files. + For example, in the Raspberry Pi BSP there is the + <filename>formfactor_0.0.bbappend</filename> file, which is an + append file used to augment the recipe that starts the build. + Furthermore, there are machine-specific settings used during + the build that are defined by the + <filename>machconfig</filename> file further down in the + directory. + Here is the <filename>machconfig</filename> + file for the Raspberry Pi BSP: + <literallayout class='monospaced'> + HAVE_TOUCHSCREEN=0 + HAVE_KEYBOARD=1 + + DISPLAY_CAN_ROTATE=0 + DISPLAY_ORIENTATION=0 + DISPLAY_DPI=133 + </literallayout> + </para> + + <note><para> + If a BSP does not have a formfactor entry, defaults are established according to + the formfactor configuration file that is installed by the main + formfactor recipe + <filename>meta/recipes-bsp/formfactor/formfactor_0.0.bb</filename>, + which is found in the + <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>. + </para></note> + </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-<replaceable>bsp_name</replaceable>/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. + </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-<replaceable>bsp_name</replaceable>/recipes-kernel/linux/linux-yocto*.bbappend + </literallayout> + </para> + + <para> + These files append your specific changes to the main kernel recipe you are using. + </para> + <para> + For your BSP, you typically want to use an existing Yocto Project kernel recipe found in the + <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</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 the BSP Layer (e.g. + the <filename>meta-<replaceable>bsp_name</replaceable>/recipes-kernel/linux</filename> directory). + </para> + <para> + Suppose you are using the <filename>linux-yocto_4.4.bb</filename> recipe to build + the kernel. + In other words, you have selected the kernel in your + <replaceable>bsp_name</replaceable><filename>.conf</filename> file by adding these types + of statements: + <literallayout class='monospaced'> + PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto" + PREFERRED_VERSION_linux-yocto ?= "4.4%" + </literallayout> + <note> + When the preferred provider is assumed by default, the + <filename>PREFERRED_PROVIDER</filename> statement does not appear in the + <replaceable>bsp_name</replaceable><filename>.conf</filename> file. + </note> + You would use the <filename>linux-yocto_4.4.bbappend</filename> + file to append specific BSP settings to the kernel, thus + configuring the kernel for your particular BSP. + </para> + + <para> + As an example, consider the following append file + used by the BSPs in <filename>meta-yocto-bsp</filename>: + <literallayout class='monospaced'> + meta-yocto-bsp/recipes-kernel/linux/linux-yocto_4.4.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-yocto-bsp</filename> + layer upstream. + <literallayout class='monospaced'> + KBRANCH_genericx86 = "standard/base" + KBRANCH_genericx86-64 = "standard/base" + + KMACHINE_genericx86 ?= "common-pc" + KMACHINE_genericx86-64 ?= "common-pc-64" + KBRANCH_edgerouter = "standard/edgerouter" + KBRANCH_beaglebone = "standard/beaglebone" + KBRANCH_mpc8315e-rdb = "standard/fsl-mpc8315e-rdb" + + SRCREV_machine_genericx86 ?= "ff4c4ef15b51f45b9106d71bf1f62fe7c02e63c2" + SRCREV_machine_genericx86-64 ?= "ff4c4ef15b51f45b9106d71bf1f62fe7c02e63c2" + SRCREV_machine_edgerouter ?= "ff4c4ef15b51f45b9106d71bf1f62fe7c02e63c2" + SRCREV_machine_beaglebone ?= "ff4c4ef15b51f45b9106d71bf1f62fe7c02e63c2" + SRCREV_machine_mpc8315e-rdb ?= "df00877ef9387b38b9601c82db57de2a1b23ce53" + + COMPATIBLE_MACHINE_genericx86 = "genericx86" + COMPATIBLE_MACHINE_genericx86-64 = "genericx86-64" + COMPATIBLE_MACHINE_edgerouter = "edgerouter" + COMPATIBLE_MACHINE_beaglebone = "beaglebone" + COMPATIBLE_MACHINE_mpc8315e-rdb = "mpc8315e-rdb" + + LINUX_VERSION_genericx86 = "4.4.3" + LINUX_VERSION_genericx86-64 = "4.4.3" + </literallayout> + This append file contains statements used to support + several BSPs that ship with the Yocto Project. + The file defines machines using the + <ulink url='&YOCTO_DOCS_REF_URL;#var-COMPATIBLE_MACHINE'><filename>COMPATIBLE_MACHINE</filename></ulink> + variable and uses the + <ulink url='&YOCTO_DOCS_REF_URL;#var-KMACHINE'><filename>KMACHINE</filename></ulink> + variable to ensure the machine name used by the OpenEmbedded + build system maps to the machine name used by the Linux Yocto + kernel. + The file also uses the optional + <ulink url='&YOCTO_DOCS_REF_URL;#var-KBRANCH'><filename>KBRANCH</filename></ulink> + variable to ensure the build process uses the + appropriate kernel branch. + </para> + + <para> + Although this particular example does not use it, the + <ulink url='&YOCTO_DOCS_REF_URL;#var-KERNEL_FEATURES'><filename>KERNEL_FEATURES</filename></ulink> + variable could be used to enable features specific to + the kernel. + The append file points to specific commits in the + <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink> + Git repository and the <filename>meta</filename> Git repository + branches to identify the exact kernel needed to build the + 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 kernel's append file and having the same + name as the kernel's main recipe file. + With all these conditions met, simply reference those files in the + <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink> + statement in the append file. + </para> + + <para> + For example, suppose you had some configuration options + in a file called <filename>network_configs.cfg</filename>. + You can place that file inside a directory named + <filename>linux-yocto</filename> and then add + a <filename>SRC_URI</filename> statement such as the + following to the append file. + When the OpenEmbedded build system builds the kernel, the + configuration options are picked up and applied. + <literallayout class='monospaced'> + SRC_URI += "file://network_configs.cfg" + </literallayout> + </para> + + <para> + To group related configurations into multiple files, you + perform a similar procedure. + Here is an example that groups separate configurations + specifically for Ethernet and graphics into their own + files and adds the configurations by using a + <filename>SRC_URI</filename> statement like the following + in your append file: + <literallayout class='monospaced'> + SRC_URI += "file://myconfig.cfg \ + file://eth.cfg \ + file://gfx.cfg" + </literallayout> + </para> + + <para> + Another variable you can use in your kernel recipe append + file is the + <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></ulink> + variable. + When you use this statement, you are extending the locations + used by the OpenEmbedded system to look for files and + patches as the recipe is processed. + </para> + + <note> + <para> + Other methods exist to accomplish grouping and defining configuration options. + For example, if you are working with a local clone of the kernel repository, + you could checkout the kernel's <filename>meta</filename> branch, make your changes, + and then push the changes to the local bare clone of the kernel. + The result is that you directly add configuration options to the + <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. + </para> + + <para> + In general, however, the Yocto Project maintainers take care of moving the + <filename>SRC_URI</filename>-specified + configuration options to the kernel's <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='requirements-and-recommendations-for-released-bsps'> + <title>Requirements and Recommendations for Released BSPs</title> + + <para> + Certain requirements exist for a released BSP to be considered + compliant with the Yocto Project. + Additionally, recommendations also exist. + This section describes the requirements and recommendations for + released BSPs. + </para> + + <section id='released-bsp-requirements'> + <title>Released BSP Requirements</title> + + <para> + Before looking at BSP requirements, you should consider the following: + <itemizedlist> + <listitem><para>The requirements here assume the BSP layer is a well-formed, "legal" + layer that can be added to the Yocto Project. + For guidelines on creating a layer that meets these base requirements, see the + "<link linkend='bsp-layers'>BSP Layers</link>" and the + "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding + and Creating Layers"</ulink> in the Yocto Project Development Manual.</para></listitem> + <listitem><para>The requirements in this section apply regardless of how you + package a BSP. + You should consult the packaging and distribution guidelines for your + specific release process. + For an example of packaging and distribution requirements, see the + "<ulink url='https://wiki.yoctoproject.org/wiki/Third_Party_BSP_Release_Process'>Third Party BSP Release Process</ulink>" + wiki page.</para></listitem> + <listitem><para>The requirements for the BSP as it is made available to a developer + are completely independent of the released form of the BSP. + For example, the BSP Metadata can be contained within a Git repository + and could have a directory structure completely different from what appears + in the officially released BSP layer.</para></listitem> + <listitem><para>It is not required that specific packages or package + modifications exist in the BSP layer, beyond the requirements for general + compliance with the Yocto Project. + For example, no requirement exists dictating that a specific kernel or + kernel version be used in a given BSP.</para></listitem> + </itemizedlist> + </para> + + <para> + Following are the requirements for a released BSP that conform to the + Yocto Project: + <itemizedlist> + <listitem><para><emphasis>Layer Name:</emphasis> + The BSP must have a layer name that follows the Yocto + Project standards. + For information on BSP layer names, see the + "<link linkend='bsp-layers'>BSP Layers</link>" section. + </para></listitem> + <listitem><para><emphasis>File System Layout:</emphasis> + When possible, use the same directory names in your + BSP layer as listed in the <filename>recipes.txt</filename> file. + In particular, you should place recipes + (<filename>.bb</filename> files) and recipe + modifications (<filename>.bbappend</filename> files) into + <filename>recipes-*</filename> subdirectories by functional area + as outlined in <filename>recipes.txt</filename>. + If you cannot find a category in <filename>recipes.txt</filename> + to fit a particular recipe, you can make up your own + <filename>recipes-*</filename> subdirectory. + You can find <filename>recipes.txt</filename> in the + <filename>meta</filename> directory of the + <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>, + or in the OpenEmbedded Core Layer + (<filename>openembedded-core</filename>) found at + <ulink url='http://git.openembedded.org/openembedded-core/tree/meta'></ulink>. + </para> + <para>Within any particular <filename>recipes-*</filename> category, the layout + should match what is found in the OpenEmbedded Core + Git repository (<filename>openembedded-core</filename>) + or the Source Directory (<filename>poky</filename>). + In other words, make sure you place related files in appropriately + related <filename>recipes-*</filename> subdirectories specific to the + recipe's function, or within a subdirectory containing a set of closely-related + recipes. + The recipes themselves should follow the general guidelines + for recipes used in the Yocto Project found in the + "<ulink url='http://openembedded.org/wiki/Styleguide'>OpenEmbedded Style Guide</ulink>". + </para></listitem> + <listitem><para><emphasis>License File:</emphasis> + You must include a license file in the + <filename>meta-<replaceable>bsp_name</replaceable></filename> directory. + This license covers the BSP Metadata as a whole. + You must specify which license to use since there is no + default license if one is not specified. + See the + <ulink url='&YOCTO_GIT_URL;/cgit.cgi/meta-raspberrypi/tree/COPYING.MIT'><filename>COPYING.MIT</filename></ulink> + file for the Raspberry Pi BSP in the + <filename>meta-raspberrypi</filename> BSP layer as an example. + </para></listitem> + <listitem><para><emphasis>README File:</emphasis> + You must include a <filename>README</filename> file in the + <filename>meta-<replaceable>bsp_name</replaceable></filename> directory. + See the + <ulink url='&YOCTO_GIT_URL;/cgit.cgi/meta-raspberrypi/tree/README'><filename>README</filename></ulink> + file for the Raspberry Pi BSP in the <filename>meta-raspberrypi</filename> BSP layer + as an example.</para> + <para>At a minimum, the <filename>README</filename> file should + contain the following: + <itemizedlist> + <listitem><para>A brief description about the hardware the BSP + targets.</para></listitem> + <listitem><para>A list of all the dependencies + on which a BSP layer depends. + These dependencies are typically a list of required layers needed + to build the BSP. + However, the dependencies should also contain information regarding + any other dependencies the BSP might have.</para></listitem> + <listitem><para>Any required special licensing information. + For example, this information includes information on + special variables needed to satisfy a EULA, + or instructions on information needed to build or distribute + binaries built from the BSP Metadata.</para></listitem> + <listitem><para>The name and contact information for the + BSP layer maintainer. + This is the person to whom patches and questions should + be sent. + For information on how to find the right person, see the + "<ulink url='&YOCTO_DOCS_DEV_URL;#how-to-submit-a-change'>How to Submit a Change</ulink>" + section in the Yocto Project Development Manual. + </para></listitem> + <listitem><para>Instructions on how to build the BSP using the BSP + layer.</para></listitem> + <listitem><para>Instructions on how to boot the BSP build from + the BSP layer.</para></listitem> + <listitem><para>Instructions on how to boot the binary images + contained in the <filename>binary</filename> directory, + if present.</para></listitem> + <listitem><para>Information on any known bugs or issues that users + should know about when either building or booting the BSP + binaries.</para></listitem> + </itemizedlist></para></listitem> + <listitem><para><emphasis>README.sources File:</emphasis> + You must include a <filename>README.sources</filename> in the + <filename>meta-<replaceable>bsp_name</replaceable></filename> directory. + This file specifies exactly where you can find the sources used to + generate the binary images contained in the + <filename>binary</filename> directory, if present. + </para></listitem> + <listitem><para><emphasis>Layer Configuration File:</emphasis> + You must include a <filename>conf/layer.conf</filename> in the + <filename>meta-<replaceable>bsp_name</replaceable></filename> directory. + This file identifies the <filename>meta-<replaceable>bsp_name</replaceable></filename> + BSP layer as a layer to the build system.</para></listitem> + <listitem><para><emphasis>Machine Configuration File:</emphasis> + You must include one or more + <filename>conf/machine/<replaceable>bsp_name</replaceable>.conf</filename> + files in the <filename>meta-<replaceable>bsp_name</replaceable></filename> directory. + These configuration files define machine targets that can be built + using the BSP layer. + Multiple machine configuration files define variations of machine + configurations that are supported by the BSP. + If a BSP supports multiple machine variations, you need to + adequately describe each variation in the BSP + <filename>README</filename> file. + Do not use multiple machine configuration files to describe disparate + hardware. + If you do have very different targets, you should create separate + BSP layers for each target. + <note>It is completely possible for a developer to structure the + working repository as a conglomeration of unrelated BSP + files, and to possibly generate BSPs targeted for release + from that directory using scripts or some other mechanism + (e.g. <filename>meta-yocto-bsp</filename> layer). + Such considerations are outside the scope of this document.</note> + </para></listitem> + </itemizedlist> + </para> + </section> + + <section id='released-bsp-recommendations'> + <title>Released BSP Recommendations</title> + + <para> + Following are recommendations for a released BSP that conforms to the + Yocto Project: + <itemizedlist> + <listitem><para><emphasis>Bootable Images:</emphasis> + BSP releases + can contain one or more bootable images. + Including bootable images allows users to easily try out the BSP + on their own hardware.</para> + <para>In some cases, it might not be convenient to include a + bootable image. + In this case, you might want to make two versions of the + BSP available: one that contains binary images, and one + that does not. + The version that does not contain bootable images avoids + unnecessary download times for users not interested in the images. + </para> + <para>If you need to distribute a BSP and include bootable images or build kernel and + filesystems meant to allow users to boot the BSP for evaluation + purposes, you should put the images and artifacts within a + <filename>binary/</filename> subdirectory located in the + <filename>meta-<replaceable>bsp_name</replaceable></filename> directory. + <note>If you do include a bootable image as part of the BSP and the image + was built by software covered by the GPL or other open source licenses, + it is your responsibility to understand + and meet all licensing requirements, which could include distribution + of source files.</note></para></listitem> + <listitem><para><emphasis>Use a Yocto Linux Kernel:</emphasis> + Kernel recipes in the BSP should be based on a Yocto Linux kernel. + Basing your recipes on these kernels reduces the costs for maintaining + the BSP and increases its scalability. + See the <filename>Yocto Linux Kernel</filename> category in the + <ulink url='&YOCTO_GIT_URL;/cgit.cgi'>Source Repositories</ulink> + for these kernels.</para></listitem> + </itemizedlist> + </para> + </section> + </section> + + <section id='customizing-a-recipe-for-a-bsp'> + <title>Customizing a Recipe for a BSP</title> + + <para> + If you plan on customizing a recipe for a particular BSP, you need to do the + following: + <itemizedlist> + <listitem><para>Create a <filename>.bbappend</filename> + file for the modified recipe. + For information on using append files, see the + "<ulink url='&YOCTO_DOCS_DEV_URL;#using-bbappend-files'>Using .bbappend Files</ulink>" + section in the Yocto Project Development Manual. + </para></listitem> + <listitem><para> + Ensure your directory structure in the BSP layer + that supports your machine is such that it can be found + by the build system. + See the example later in this section for more information. + </para></listitem> + <listitem><para> + Put the append file in a directory whose name matches + the machine's name and is located in an appropriate + sub-directory inside the BSP layer (i.e. + <filename>recipes-bsp</filename>, <filename>recipes-graphics</filename>, + <filename>recipes-core</filename>, and so forth). + </para></listitem> + <listitem><para>Place the BSP-specific files in the proper directory + inside the BSP layer. + How expansive the layer is affects where you must place these files. + For example, if your layer supports several different machine types, + you need to be sure your layer's directory structure includes hierarchy + that separates the files out according to machine. + If your layer does not support multiple machines, the layer would not + have that additional hierarchy and the files would obviously not be + able to reside in a machine-specific directory. + </para></listitem> + </itemizedlist> + </para> + + <para> + Following is a specific example to help you better understand the process. + Consider an example that customizes a recipe by adding + a BSP-specific configuration file named <filename>interfaces</filename> to the + <filename>init-ifupdown_1.0.bb</filename> recipe for machine "xyz" where the + BSP layer also supports several other machines. + Do the following: + <orderedlist> + <listitem><para>Edit the <filename>init-ifupdown_1.0.bbappend</filename> file so that it + contains the following: + <literallayout class='monospaced'> + FILESEXTRAPATHS_prepend := "${THISDIR}/files:" + </literallayout> + The append file needs to be in the + <filename>meta-xyz/recipes-core/init-ifupdown</filename> directory. + </para></listitem> + <listitem><para>Create and place the new <filename>interfaces</filename> + configuration file in the BSP's layer here: + <literallayout class='monospaced'> + meta-xyz/recipes-core/init-ifupdown/files/xyz-machine-one/interfaces + </literallayout> + <note> + If the <filename>meta-xyz</filename> layer did not support + multiple machines, you would place the + <filename>interfaces</filename> configuration file in the + layer here: + <literallayout class='monospaced'> + meta-xyz/recipes-core/init-ifupdown/files/interfaces + </literallayout> + </note> + The + <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></ulink> + variable in the append files extends the search path + the build system uses to find files during the build. + Consequently, for this example you need to have the + <filename>files</filename> directory in the same location + as your append file.</para></listitem> + </orderedlist> + </para> + </section> + + <section id='bsp-licensing-considerations'> + <title>BSP Licensing Considerations</title> + + <para> + In some cases, a BSP contains separately licensed Intellectual Property (IP) + for a component or components. + For these cases, you are required to accept the terms of a commercial or other + type of license that requires some kind of explicit End User License Agreement (EULA). + Once the license is accepted, the OpenEmbedded build system can then build and + include the corresponding component in the final BSP image. + If the BSP is available as a pre-built image, you can download the image after + agreeing to the license or EULA. + </para> + + <para> + You could find that some separately licensed components that are essential + for normal operation of the system might not have an unencumbered (or free) + substitute. + Without these essential components, the system would be non-functional. + Then again, you might find that other licensed components that are simply + 'good-to-have' or purely elective do have an unencumbered, free replacement + component that you can use rather than agreeing to the separately licensed component. + Even for components essential to the system, you might find an unencumbered component + that is not identical but will work as a less-capable version of the + licensed version in the BSP recipe. + </para> + + <para> + For cases where you can substitute a free component and still + maintain the system's functionality, the "Downloads" page from the + <ulink url='&YOCTO_HOME_URL;'>Yocto Project website's</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 your + simplest and most preferred options. + Use of these substitutions of course assumes the resulting functionality meets + system requirements. + </para> + + <para> + If however, a non-encumbered version is unavailable or + it provides unsuitable functionality or quality, you can use an encumbered + version. + </para> + + <para> + A couple different methods exist within the OpenEmbedded build system to + satisfy the licensing requirements for an encumbered BSP. + The following list describes them in order of preference: + <orderedlist> + <listitem><para><emphasis>Use the + <ulink url='&YOCTO_DOCS_REF_URL;#var-LICENSE_FLAGS'><filename>LICENSE_FLAGS</filename></ulink> + variable to define the recipes that have commercial or other + types of specially-licensed packages:</emphasis> + For each of those recipes, you can + specify a matching license string in a + <filename>local.conf</filename> variable named + <ulink url='&YOCTO_DOCS_REF_URL;#var-LICENSE_FLAGS_WHITELIST'><filename>LICENSE_FLAGS_WHITELIST</filename></ulink>. + Specifying the matching license string signifies that you agree to the license. + Thus, the build system can build the corresponding recipe and include + the component in the image. + See the + "<ulink url='&YOCTO_DOCS_REF_URL;#enabling-commercially-licensed-recipes'>Enabling + Commercially Licensed Recipes</ulink>" section in the Yocto Project Reference + Manual for details on how to use these variables.</para> + <para>If you build as you normally would, without + specifying any recipes in the + <filename>LICENSE_FLAGS_WHITELIST</filename>, the build stops and + provides you with the list of recipes that you have + tried to include in the image that need entries in + the <filename>LICENSE_FLAGS_WHITELIST</filename>. + Once you enter the appropriate license flags into the whitelist, + 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> + <para>Once the appropriate license flags are on the white list + in the <filename>LICENSE_FLAGS_WHITELIST</filename> variable, you + can build the encumbered image with no change at all + to the normal build process.</para></listitem> + <listitem><para><emphasis>Get a pre-built version of the BSP:</emphasis> + You can get this type of BSP by visiting the + "Downloads" page of the + <ulink url='&YOCTO_HOME_URL;'>Yocto Project website</ulink>. + You can download BSP tarballs that contain proprietary components + after agreeing to the licensing + requirements of each of the individually encumbered + packages as part of the download process. + Obtaining the BSP this way allows you to access an encumbered + image immediately after agreeing to the + click-through license agreements presented by the + website. + Note that if you want to build the image + yourself using the recipes contained within the BSP + tarball, you will still need to create an + appropriate <filename>LICENSE_FLAGS_WHITELIST</filename> to match the + encumbered recipes in the BSP.</para></listitem> + </orderedlist> + </para> + + <note> + Pre-compiled images are bundled with + a time-limited kernel that runs for a + predetermined amount of time (10 days) before it forces + the system to reboot. + This limitation is meant to discourage direct redistribution + of the image. + You must eventually rebuild the image if you want to remove this restriction. + </note> + </section> + + <section id='using-the-yocto-projects-bsp-tools'> + <title>Using the Yocto Project's BSP Tools</title> + + <para> + The Yocto Project includes a couple of tools that enable + you to create a <link linkend='bsp-layers'>BSP layer</link> + from scratch and do basic configuration and maintenance + of the kernel without ever looking at a Metadata file. + These tools are <filename>yocto-bsp</filename> and <filename>yocto-kernel</filename>, + respectively. + </para> + + <para> + The following sections describe the common location and help features as well + as provide details for the + <filename>yocto-bsp</filename> and <filename>yocto-kernel</filename> tools. + </para> + + <section id='common-features'> + <title>Common Features</title> + + <para> + Designed to have a command interface somewhat like + <ulink url='&YOCTO_DOCS_DEV_URL;#git'>Git</ulink>, each + tool is structured as a set of sub-commands under a + top-level command. + The top-level command (<filename>yocto-bsp</filename> + or <filename>yocto-kernel</filename>) itself does + nothing but invoke or provide help on the sub-commands + it supports. + </para> + + <para> + Both tools reside in the <filename>scripts/</filename> subdirectory + of the <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>. + Consequently, to use the scripts, you must <filename>source</filename> the + environment just as you would when invoking a build: + <literallayout class='monospaced'> + $ source oe-init-build-env <replaceable>build_dir</replaceable> + </literallayout> + </para> + + <para> + The most immediately useful function is to get help on both tools. + The built-in help system makes it easy to drill down at + any time and view the syntax required for any specific command. + Simply enter the name of the command with the <filename>help</filename> + switch: + <literallayout class='monospaced'> + $ yocto-bsp help + Usage: + + Create a customized Yocto BSP layer. + + usage: yocto-bsp [--version] [--help] COMMAND [ARGS] + + Current 'yocto-bsp' commands are: + create Create a new Yocto BSP + list List available values for options and BSP properties + + See 'yocto-bsp help COMMAND' for more information on a specific command. + + + Options: + --version show program's version number and exit + -h, --help show this help message and exit + -D, --debug output debug information + </literallayout> + </para> + + <para> + Similarly, entering just the name of a sub-command shows the detailed usage + for that sub-command: + <literallayout class='monospaced'> + $ yocto-bsp create + ERROR:root:Wrong number of arguments, exiting + + Usage: + + Create a new Yocto BSP + + usage: yocto-bsp create <bsp-name> <karch> [-o <DIRNAME> | --outdir <DIRNAME>] + [-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>] + + This command creates a Yocto BSP based on the specified parameters. + The new BSP will be a new Yocto BSP layer contained by default within + the top-level directory specified as 'meta-bsp-name'. The -o option + can be used to place the BSP layer in a directory with a different + name and location. + + The value of the 'karch' parameter determines the set of files that + will be generated for the BSP, along with the specific set of + 'properties' that will be used to fill out the BSP-specific portions + of the BSP. The possible values for the 'karch' parameter can be + listed via 'yocto-bsp list karch'. + + ... + </literallayout> + </para> + + <para> + For any sub-command, you can use the word "help" option just before the + sub-command to get more extensive documentation: + <literallayout class='monospaced'> + $ yocto-bsp help create + + NAME + yocto-bsp create - Create a new Yocto BSP + + SYNOPSIS + yocto-bsp create <bsp-name> <karch> [-o <DIRNAME> | --outdir <DIRNAME>] + [-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>] + + DESCRIPTION + This command creates a Yocto BSP based on the specified + parameters. The new BSP will be a new Yocto BSP layer contained + by default within the top-level directory specified as + 'meta-bsp-name'. The -o option can be used to place the BSP layer + in a directory with a different name and location. + + ... + </literallayout> + </para> + + <para> + Now that you know where these two commands reside and how to access information + on them, you should find it relatively straightforward to discover the commands + necessary to create a BSP and perform basic kernel maintenance on that BSP using + the tools. + <note> + You can also use the <filename>yocto-layer</filename> tool to create + a "generic" layer. + For information on this tool, see the + "<ulink url='&YOCTO_DOCS_DEV_URL;#creating-a-general-layer-using-the-yocto-layer-script'>Creating a General Layer Using the yocto-layer Script</ulink>" + section in the Yocto Project Development Guide. + </note> + </para> + + <para> + The next sections provide a concrete starting point to expand on a few points that + might not be immediately obvious or that could use further explanation. + </para> + </section> + + + <section id='creating-a-new-bsp-layer-using-the-yocto-bsp-script'> + <title>Creating a new BSP Layer Using the yocto-bsp Script</title> + + <para> + The <filename>yocto-bsp</filename> script creates a new + <link linkend='bsp-layers'>BSP layer</link> for any architecture supported + by the Yocto Project, as well as QEMU versions of the same. + The default mode of the script's operation is to prompt you for information needed + to generate the BSP layer. + </para> + + <para> + For the current set of BSPs, the script prompts you for various important + parameters such as: + <itemizedlist> + <listitem><para>The kernel to use</para></listitem> + <listitem><para>The branch of that kernel to use (or re-use)</para></listitem> + <listitem><para>Whether or not to use X, and if so, which drivers to use</para></listitem> + <listitem><para>Whether to turn on SMP</para></listitem> + <listitem><para>Whether the BSP has a keyboard</para></listitem> + <listitem><para>Whether the BSP has a touchscreen</para></listitem> + <listitem><para>Remaining configurable items associated with the BSP</para></listitem> + </itemizedlist> + </para> + + <para> + You use the <filename>yocto-bsp create</filename> sub-command to create + a new BSP layer. + This command requires you to specify a particular kernel architecture + (<filename>karch</filename>) on which to base the BSP. + Assuming you have sourced the environment, you can use the + <filename>yocto-bsp list karch</filename> sub-command to list the + architectures available for BSP creation as follows: + <literallayout class='monospaced'> + $ yocto-bsp list karch + Architectures available: + powerpc + x86_64 + i386 + arm + qemu + mips + mips64 + </literallayout> + </para> + + <para> + The remainder of this section presents an example that uses + <filename>myarm</filename> as the machine name and <filename>qemu</filename> + as the machine architecture. + Of the available architectures, <filename>qemu</filename> is the only architecture + that causes the script to prompt you further for an actual architecture. + In every other way, this architecture is representative of how creating a BSP for + an actual machine would work. + The reason the example uses this architecture is because it is an emulated architecture + and can easily be followed without requiring actual hardware. + </para> + + <para> + As the <filename>yocto-bsp create</filename> command runs, default values for + the prompts appear in brackets. + Pressing enter without supplying anything on the command line or pressing enter + with an invalid response causes the script to accept the default value. + Once the script completes, the new <filename>meta-myarm</filename> BSP layer + is created in the current working directory. + This example assumes you have sourced the + <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink> + setup script. + </para> + + <para> + Following is the complete example: + <literallayout class='monospaced'> + $ yocto-bsp create myarm qemu + Checking basic git connectivity... + Done. + + Which qemu architecture would you like to use? [default: i386] + 1) i386 (32-bit) + 2) x86_64 (64-bit) + 3) ARM (32-bit) + 4) PowerPC (32-bit) + 5) MIPS (32-bit) + 6) MIPS64 (64-bit) + 3 + Would you like to use the default (4.1) kernel? (y/n) [default: y] + Do you need a new machine branch for this BSP (the alternative is to re-use an existing branch)? [y/n] [default: y] + Getting branches from remote repo git://git.yoctoproject.org/linux-yocto-4.1.git... + Please choose a machine branch to base your new BSP branch on: [default: standard/base] + 1) standard/arm-versatile-926ejs + 2) standard/base + 3) standard/beagleboard + 4) standard/beaglebone + 5) standard/edgerouter + 6) standard/fsl-mpc8315e-rdb + 7) standard/mti-malta32 + 8) standard/mti-malta64 + 9) standard/qemuarm64 + 10) standard/qemuppc + 1 + Would you like SMP support? (y/n) [default: y] + Does your BSP have a touchscreen? (y/n) [default: n] + Does your BSP have a keyboard? (y/n) [default: y] + + New qemu BSP created in meta-myarm + </literallayout> + Take a closer look at the example now: + <orderedlist> + <listitem><para>For the QEMU architecture, + the script first prompts you for which emulated architecture to use. + In the example, we use the ARM architecture. + </para></listitem> + <listitem><para>The script then prompts you for the kernel. + The default 4.4 kernel is acceptable. + So, the example accepts the default. + If you enter 'n', the script prompts you to further enter the kernel + you do want to use.</para></listitem> + <listitem><para>Next, the script asks whether you would like to have a new + branch created especially for your BSP in the local + <ulink url='&YOCTO_DOCS_DEV_URL;#local-kernel-files'>Linux Yocto Kernel</ulink> + Git repository . + If not, then the script re-uses an existing branch.</para> + <para>In this example, the default (or "yes") is accepted. + Thus, a new branch is created for the BSP rather than using a common, shared + branch. + The new branch is the branch committed to for any patches you might later add. + The reason a new branch is the default is that typically + new BSPs do require BSP-specific patches. + The tool thus assumes that most of time a new branch is required. + </para></listitem> + <listitem><para>Regardless of which choice you make in the previous step, + you are now given the opportunity to select a particular machine branch on + which to base your new BSP-specific machine branch + (or to re-use if you had elected to not create a new branch). + Because this example is generating an ARM-based BSP, the example + uses <filename>#1</filename> at the prompt, which selects the ARM-versatile branch. + </para></listitem> + <listitem><para>The remainder of the prompts are routine. + Defaults are accepted for each.</para></listitem> + <listitem><para>By default, the script creates the new BSP Layer in the + current working directory of the + <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>, + (i.e. <filename>poky/build</filename>). + </para></listitem> + </orderedlist> + </para> + + <para> + Once the BSP Layer is created, you must add it to your + <filename>bblayers.conf</filename> file. + Here is an example: + <literallayout class='monospaced'> + BBLAYERS = ? " \ + /usr/local/src/yocto/meta \ + /usr/local/src/yocto/meta-poky \ + /usr/local/src/yocto/meta-yocto-bsp \ + /usr/local/src/yocto/meta-myarm \ + " + </literallayout> + Adding the layer to this file allows the build system to build the BSP and + the <filename>yocto-kernel</filename> tool to be able to find the layer and + other Metadata it needs on which to operate. + </para> + </section> + + <section id='managing-kernel-patches-and-config-items-with-yocto-kernel'> + <title>Managing Kernel Patches and Config Items with yocto-kernel</title> + + <para> + Assuming you have created a <link linkend='bsp-layers'>BSP Layer</link> using + <link linkend='creating-a-new-bsp-layer-using-the-yocto-bsp-script'> + <filename>yocto-bsp</filename></link> and you added it to your + <ulink url='&YOCTO_DOCS_REF_URL;#var-BBLAYERS'><filename>BBLAYERS</filename></ulink> + variable in the <filename>bblayers.conf</filename> file, you can now use + the <filename>yocto-kernel</filename> script to add patches and configuration + items to the BSP's kernel. + </para> + + <para> + The <filename>yocto-kernel</filename> script allows you to add, remove, and list patches + and kernel config settings to a BSP's kernel + <filename>.bbappend</filename> file. + All you need to do is use the appropriate sub-command. + Recall that the easiest way to see exactly what sub-commands are available + is to use the <filename>yocto-kernel</filename> built-in help as follows: + <literallayout class='monospaced'> + $ yocto-kernel --help + Usage: + + Modify and list Yocto BSP kernel config items and patches. + + usage: yocto-kernel [--version] [--help] COMMAND [ARGS] + + Current 'yocto-kernel' commands are: + config list List the modifiable set of bare kernel config options for a BSP + config add Add or modify bare kernel config options for a BSP + config rm Remove bare kernel config options from a BSP + patch list List the patches associated with a BSP + patch add Patch the Yocto kernel for a BSP + patch rm Remove patches from a BSP + feature list List the features used by a BSP + feature add Have a BSP use a feature + feature rm Have a BSP stop using a feature + features list List the features available to BSPs + feature describe Describe a particular feature + feature create Create a new BSP-local feature + feature destroy Remove a BSP-local feature + + See 'yocto-kernel help COMMAND' for more information on a specific command. + + + + Options: + --version show program's version number and exit + -h, --help show this help message and exit + -D, --debug output debug information + </literallayout> + </para> + + <para> + The <filename>yocto-kernel patch add</filename> sub-command allows you to add a + patch to a BSP. + The following example adds two patches to the <filename>myarm</filename> BSP: + <literallayout class='monospaced'> + $ yocto-kernel patch add myarm ~/test.patch + Added patches: + test.patch + + $ yocto-kernel patch add myarm ~/yocto-testmod.patch + Added patches: + yocto-testmod.patch + </literallayout> + <note>Although the previous example adds patches one at a time, it is possible + to add multiple patches at the same time.</note> + </para> + + <para> + You can verify patches have been added by using the + <filename>yocto-kernel patch list</filename> sub-command. + Here is an example: + <literallayout class='monospaced'> + $ yocto-kernel patch list myarm + The current set of machine-specific patches for myarm is: + 1) test.patch + 2) yocto-testmod.patch + </literallayout> + </para> + + <para> + You can also use the <filename>yocto-kernel</filename> script to + remove a patch using the <filename>yocto-kernel patch rm</filename> sub-command. + Here is an example: + <literallayout class='monospaced'> + $ yocto-kernel patch rm myarm + Specify the patches to remove: + 1) test.patch + 2) yocto-testmod.patch + 1 + Removed patches: + test.patch + </literallayout> + </para> + + <para> + Again, using the <filename>yocto-kernel patch list</filename> sub-command, + you can verify that the patch was in fact removed: + <literallayout class='monospaced'> + $ yocto-kernel patch list myarm + The current set of machine-specific patches for myarm is: + 1) yocto-testmod.patch + </literallayout> + </para> + + <para> + In a completely similar way, you can use the <filename>yocto-kernel config add</filename> + sub-command to add one or more kernel config item settings to a BSP. + The following commands add a couple of config items to the + <filename>myarm</filename> BSP: + <literallayout class='monospaced'> + $ yocto-kernel config add myarm CONFIG_MISC_DEVICES=y + Added item: + CONFIG_MISC_DEVICES=y + + $ yocto-kernel config add myarm CONFIG_YOCTO_TESTMOD=y + Added item: + CONFIG_YOCTO_TESTMOD=y + </literallayout> + <note> + Although the previous example adds config items one at a time, it is possible + to add multiple config items at the same time. + </note> + </para> + + <para> + You can list the config items now associated with the BSP. + Doing so shows you the config items you added as well as others associated + with the BSP: + <literallayout class='monospaced'> + $ yocto-kernel config list myarm + The current set of machine-specific kernel config items for myarm is: + 1) CONFIG_MISC_DEVICES=y + 2) CONFIG_YOCTO_TESTMOD=y + </literallayout> + </para> + + <para> + Finally, you can remove one or more config items using the + <filename>yocto-kernel config rm</filename> sub-command in a manner + completely analogous to <filename>yocto-kernel patch rm</filename>. + </para> + </section> + </section> +</chapter> |
