| <!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_REF_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 |
| "<link linkend='developing-a-board-support-package-bsp'>Developing a Board Support Package (BSP)</link>" |
| section. |
| 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;#working-with-yocto-project-source-files'>Working With Yocto Project Source Files</ulink>" |
| section also in the Yocto Project Development Tasks 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_REF_URL;#build-directory'>Build Directory</ulink>, |
| which is established after you run the OpenEmbedded build environment |
| setup script (i.e. |
| <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</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 Tasks Manual. |
| </para> |
| </section> |
| |
| <section id='preparing-your-build-host-to-work-with-bsp-layers'> |
| <title>Preparing Your Build Host to Work With BSP Layers</title> |
| |
| <para> |
| This section describes how to get your build host ready |
| to work with BSP layers. |
| Once you have the host set up, you can create the layer |
| as described in the |
| "<link linkend='creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a new BSP Layer Using the yocto-bsp Script</link>" |
| section. |
| <note> |
| For structural information on BSPs, see the |
| <link linkend='bsp-filelayout'>Example Filesystem Layout</link> |
| section. |
| </note> |
| <orderedlist> |
| <listitem><para> |
| <emphasis>Set Up the Build Environment:</emphasis> |
| Be sure you are set up to use BitBake in a shell. |
| See the |
| "<ulink url='&YOCTO_DOCS_DEV_URL;#setting-up-the-development-host-to-use-the-yocto-project'>Setting Up the Development Host to Use the Yocto Project</ulink>" |
| section in the Yocto Project Development Tasks Manual for information |
| on how to get a build host ready that is either a native |
| Linux machine or a machine that uses CROPS. |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Clone the <filename>poky</filename> Repository:</emphasis> |
| You need to have a local copy of the Yocto Project |
| <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink> |
| (i.e. a local <filename>poky</filename> repository). |
| See the |
| "<ulink url='&YOCTO_DOCS_DEV_URL;#cloning-the-poky-repository'>Cloning the <filename>poky</filename> Repository</ulink>" |
| and possibly the |
| "<ulink url='&YOCTO_DOCS_DEV_URL;#checking-out-by-branch-in-poky'>Checking Out by Branch in Poky</ulink>" |
| and |
| "<ulink url='&YOCTO_DOCS_DEV_URL;#checkout-out-by-tag-in-poky'>Checking Out by Tag in Poky</ulink>" |
| sections all in the Yocto Project Development Tasks Manual for |
| information on how to clone the <filename>poky</filename> |
| repository and check out the appropriate branch for your work. |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Determine the BSP Layer You Want:</emphasis> |
| The Yocto Project supports many BSPs, which are maintained in |
| their own layers or in layers designed to contain several |
| BSPs. |
| To get an idea of machine support through BSP layers, you can |
| look at the |
| <ulink url='&YOCTO_RELEASE_DL_URL;/machines'>index of machines</ulink> |
| for the release. |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Optionally Clone the |
| <filename>meta-intel</filename> BSP Layer:</emphasis> |
| If your hardware is based on current Intel CPUs and devices, |
| you can leverage this BSP layer. |
| For details on the <filename>meta-intel</filename> BSP layer, |
| see the layer's |
| <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi/meta-intel/tree/README'><filename>README</filename></ulink> |
| file. |
| <orderedlist> |
| <listitem><para> |
| <emphasis>Navigate to Your Source Directory:</emphasis> |
| Typically, you set up the |
| <filename>meta-intel</filename> Git repository |
| inside the |
| <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink> |
| (e.g. <filename>poky</filename>). |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Clone the Layer:</emphasis> |
| <literallayout class='monospaced'> |
| $ git clone git://git.yoctoproject.org/meta-intel.git |
| Cloning into 'meta-intel'... |
| remote: Counting objects: 14224, done. |
| remote: Compressing objects: 100% (4591/4591), done. |
| remote: Total 14224 (delta 8245), reused 13985 (delta 8006) |
| Receiving objects: 100% (14224/14224), 4.29 MiB | 2.90 MiB/s, done. |
| Resolving deltas: 100% (8245/8245), done. |
| Checking connectivity... done. |
| </literallayout> |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Check Out the Proper Branch:</emphasis> |
| The branch you check out for |
| <filename>meta-intel</filename> must match the same |
| branch you are using for the Yocto Project release |
| (e.g. &DISTRO_NAME_NO_CAP;): |
| <literallayout class='monospaced'> |
| $ git checkout <replaceable>branch_name</replaceable> |
| </literallayout> |
| For an example on how to discover branch names and |
| checkout on a branch, see the |
| "<ulink url='&YOCTO_DOCS_DEV_URL;#checking-out-by-branch-in-poky'>Checking Out By Branch in Poky</ulink>" |
| section in the Yocto Project Development Tasks Manual. |
| </para></listitem> |
| </orderedlist> |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Optionally Set Up an Alternative BSP Layer:</emphasis> |
| If your hardware can be more closely leveraged to an |
| existing BSP not within the <filename>meta-intel</filename> |
| BSP layer, you can clone that BSP layer.</para> |
| |
| <para>The process is identical to the process used for the |
| <filename>meta-intel</filename> layer except for the layer's |
| name. |
| For example, if you determine that your hardware most |
| closely matches the <filename>meta-minnow</filename>, |
| clone that layer: |
| <literallayout class='monospaced'> |
| $ git clone git://git.yoctoproject.org/meta-minnow |
| Cloning into 'meta-minnow'... |
| remote: Counting objects: 456, done. |
| remote: Compressing objects: 100% (283/283), done. |
| remote: Total 456 (delta 163), reused 384 (delta 91) |
| Receiving objects: 100% (456/456), 96.74 KiB | 0 bytes/s, done. |
| Resolving deltas: 100% (163/163), done. |
| Checking connectivity... done. |
| </literallayout> |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Initialize the Build Environment:</emphasis> |
| While in the root directory of the Source Directory (i.e. |
| <filename>poky</filename>), run the |
| <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink> |
| environment setup script to define the OpenEmbedded |
| build environment on your build host. |
| <literallayout class='monospaced'> |
| $ source &OE_INIT_FILE; |
| </literallayout> |
| Among other things, the script creates the |
| <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>, |
| which is <filename>build</filename> in this case |
| and is located in the |
| <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>. |
| After the script runs, your current working directory |
| is set to the <filename>build</filename> directory. |
| </para></listitem> |
| </orderedlist> |
| </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_REF_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_REF_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_REF_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_REF_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 machine-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_REF_URL;#source-directory'>Source Directory</ulink> |
| at <filename>meta/recipes-kernel/linux</filename>. |
| You can append machine-specific changes to the kernel recipe |
| by using a similarly named append file, which is located in |
| the BSP Layer for your target device (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 |
| <ulink url='&YOCTO_DOCS_REF_URL;#var-PREFERRED_PROVIDER'><filename>PREFERRED_PROVIDER</filename></ulink> |
| and |
| <ulink url='&YOCTO_DOCS_REF_URL;#var-PREFERRED_VERSION'><filename>PREFERRED_VERSION</filename></ulink> |
| statements as follows: |
| <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> |
| You can find more information on what your append file |
| should contain in the |
| "<ulink url='&YOCTO_DOCS_KERNEL_URL;#creating-the-append-file'>Creating the Append File</ulink>" |
| section in the Yocto Project Linux Kernel Development |
| Manual. |
| </para> |
| </section> |
| </section> |
| |
| <section id='developing-a-board-support-package-bsp'> |
| <title>Developing a Board Support Package (BSP)</title> |
| |
| <para> |
| This section contains the high-level procedure you can follow |
| to create a BSP using the Yocto Project's |
| <link linkend='using-the-yocto-projects-bsp-tools'>BSP Tools</link>. |
| Although not required for BSP creation, the |
| <filename>meta-intel</filename> repository, which contains |
| many BSPs supported by the Yocto Project, is part of the |
| example. |
| </para> |
| |
| <para> |
| For an example that shows how to create a new layer using |
| the tools, see the |
| "<link linkend='creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</link>" |
| section. |
| </para> |
| |
| <para> |
| The following illustration and list summarize the BSP |
| creation general workflow. |
| </para> |
| |
| <para> |
| <imagedata fileref="figures/bsp-dev-flow.png" width="7in" depth="5in" align="center" scalefit="1" /> |
| </para> |
| |
| <para> |
| <orderedlist> |
| <listitem><para> |
| <emphasis>Set up Your Host Development System to Support |
| Development Using the Yocto Project</emphasis>: |
| See the |
| "<ulink url='&YOCTO_DOCS_QS_URL;#yp-resources'>Setting Up to Use the Yocto Project</ulink>" |
| section in the Yocto Project Quick Start for options on how |
| to get a build host ready to use the Yocto Project. |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Establish the <filename>meta-intel</filename> |
| Repository on Your System:</emphasis> |
| Having local copies of these supported BSP layers on |
| your system gives you access to layers you might be able |
| to build on or modify to create your BSP. |
| For information on how to get these files, see the |
| "<link linkend='preparing-your-build-host-to-work-with-bsp-layers'>Preparing Your Build Host to Work with BSP Layers</link>" |
| section. |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Create Your Own BSP Layer Using the |
| <link linkend='creating-a-new-bsp-layer-using-the-yocto-bsp-script'><filename>yocto-bsp</filename></link> |
| script:</emphasis> |
| Layers are ideal for isolating and storing work for a |
| given piece of hardware. |
| A layer is really just a location or area in which you |
| place the recipes and configurations for your BSP. |
| In fact, a BSP is, in itself, a special type of layer. |
| The simplest way to create a new BSP layer that is |
| compliant with the Yocto Project is to use the |
| <filename>yocto-bsp</filename> script. |
| For information about that script, see the |
| "<link linkend='creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</link>" |
| section.</para> |
| |
| <para>Another example that illustrates a layer |
| is an application. |
| Suppose you are creating an application that has |
| library or other dependencies in order for it to |
| compile and run. |
| The layer, in this case, would be where all the |
| recipes that define those dependencies are kept. |
| The key point for a layer is that it is an isolated |
| area that contains all the relevant information for |
| the project that the OpenEmbedded build system knows |
| about. |
| For more information on layers, see the |
| "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>" |
| section in the Yocto Project Development Tasks Manual. |
| For more information on BSP layers, see the |
| "<link linkend='bsp-layers'>BSP Layers</link>" |
| section. |
| <note><title>Notes</title> |
| <para>Five BSPs exist that are part of the Yocto |
| Project release: |
| <filename>beaglebone</filename> (ARM), |
| <filename>mpc8315e</filename> (PowerPC), |
| and <filename>edgerouter</filename> (MIPS). |
| The recipes and configurations for these five BSPs |
| are located and dispersed within the |
| <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>. |
| </para> |
| |
| <para>Three core Intel BSPs exist as part of the Yocto |
| Project release in the |
| <filename>meta-intel</filename> layer: |
| <itemizedlist> |
| <listitem><para> |
| <filename>intel-core2-32</filename>, |
| which is a BSP optimized for the Core2 family of CPUs |
| as well as all CPUs prior to the Silvermont core. |
| </para></listitem> |
| <listitem><para> |
| <filename>intel-corei7-64</filename>, |
| which is a BSP optimized for Nehalem and later |
| Core and Xeon CPUs as well as Silvermont and later |
| Atom CPUs, such as the Baytrail SoCs. |
| </para></listitem> |
| <listitem><para> |
| <filename>intel-quark</filename>, |
| which is a BSP optimized for the Intel Galileo |
| gen1 & gen2 development boards. |
| </para></listitem> |
| </itemizedlist></para> |
| </note></para> |
| |
| <para>When you set up a layer for a new BSP, you should |
| follow a standard layout. |
| This layout is described in the |
| "<link linkend='bsp-filelayout'>Example Filesystem Layout</link>" |
| section. |
| In the standard layout, you will notice a suggested |
| structure for recipes and configuration information. |
| You can see the standard layout for a BSP by examining |
| any supported BSP found in the |
| <filename>meta-intel</filename> layer inside the Source |
| Directory. |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Make Configuration Changes to Your New BSP |
| Layer:</emphasis> |
| The standard BSP layer structure organizes the files |
| you need to edit in <filename>conf</filename> and |
| several <filename>recipes-*</filename> |
| directories within the BSP layer. |
| Configuration changes identify where your new layer |
| is on the local system and identify which kernel you |
| are going to use. |
| When you run the <filename>yocto-bsp</filename> script, |
| you are able to interactively configure many things for |
| the BSP (e.g. keyboard, touchscreen, and so forth). |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Make Recipe Changes to Your New BSP |
| Layer:</emphasis> |
| Recipe changes include altering recipes |
| (<filename>.bb</filename> files), removing recipes you |
| do not use, and adding new recipes or append files |
| (<filename>.bbappend</filename>) that you need to |
| support your hardware. |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Prepare for the Build:</emphasis> |
| Once you have made all the changes to your BSP layer, |
| there remains a few things you need to do for the |
| OpenEmbedded build system in order for it to create |
| your image. |
| You need to get the build environment ready by |
| sourcing an environment setup script |
| (i.e. <filename>oe-init-build-env</filename>) |
| and you need to be sure two key configuration |
| files are configured appropriately: the |
| <filename>conf/local.conf</filename> and the |
| <filename>conf/bblayers.conf</filename> file. |
| You must make the OpenEmbedded build system aware |
| of your new layer. |
| See the |
| "<ulink url='&YOCTO_DOCS_DEV_URL;#enabling-your-layer'>Enabling Your Layer</ulink>" |
| section in the Yocto Project Development Tasks Manual |
| for information on how to let the build system |
| know about your new layer.</para> |
| |
| <para>The entire process for building an image is |
| overviewed in the section |
| "<ulink url='&YOCTO_DOCS_QS_URL;#qs-building-images'>Building Images</ulink>" section |
| of the Yocto Project Quick Start. |
| You might want to reference this information. |
| </para></listitem> |
| <listitem><para> |
| <emphasis>Build the Image:</emphasis> |
| The OpenEmbedded build system uses the BitBake tool |
| to build images based on the type of image you want to |
| create. |
| You can find more information about BitBake in the |
| <ulink url='&YOCTO_DOCS_BB_URL;'>BitBake User Manual</ulink>. |
| </para> |
| |
| <para>The build process supports several types of |
| images to satisfy different needs. |
| See the |
| "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>" |
| chapter in the Yocto Project Reference Manual for |
| information on supported images. |
| </para></listitem> |
| </orderedlist> |
| </para> |
| </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 Tasks 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_REF_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'>Submitting a Change to the Yocto Project</ulink>" |
| section in the Yocto Project Development Tasks 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 in Your Layer</ulink>" |
| section in the Yocto Project Development Tasks 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_REF_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_REF_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>bitbake-layers</filename> script to create |
| a "generic" layer. |
| For information on using this script to create a layer, see the |
| "<ulink url='&YOCTO_DOCS_DEV_URL;#creating-a-general-layer-using-the-bitbake-layers-script'>Creating a General Layer Using the <filename>bitbake-layers</filename> Script</ulink>" |
| section in the Yocto Project Development Tasks Manual. |
| </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 (4.8) 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-4.8.git... |
| Please choose a machine branch to base this BSP on: [default: standard/base] |
| 1) standard/arm-versatile-926ejs |
| 2) standard/base |
| 3) standard/beaglebone |
| 4) standard/edgerouter |
| 5) standard/fsl-mpc8315e-rdb |
| 6) standard/mti-malta32 |
| 7) standard/mti-malta64 |
| 8) standard/qemuarm64 |
| 9) 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 4.8 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 |
| Linux Yocto Kernel 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_REF_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> |