Difference between revisions of "Application Notes: Making Changes to Yocto Meta-Layers"

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Latest revision as of 11:13, 3 December 2019

This is a simple example that shows how to add a New Machine in Yocto bitbake meta layer.

Introduction

In Yocto terminology a machine is the target device for which the Yocto image is built. The example machine in this article is CompuLab's CL-SOM-iMX8.

Adding a New Machine

Adding a new machine to the Yocto Project is a straightforward process.
This section describes how to add machines that are similar to those that the Yocto Project already supports.
For a complete example that shows how to add a new machine, see the “Creating a New BSP Layer Using the yocto-bsp Script” section in the Yocto Project Board Support Package (BSP) Developer’s Guide.

Adding the Machine Configuration File

To add a new machine, you need to add a new machine configuration file to the layer’s conf/machine directory.
This configuration file provides details about the device you are adding.

The OpenEmbedded build system uses the root name of the machine configuration file to reference the new machine.
For example, given a machine configuration file named cl-som-imx8.conf, the build system recognizes the machine as “cl-som-imx8”.

The most important variables you must set in your machine configuration file or include from a lower-level configuration file are as follows:

  1. TARGET_ARCH (e.g. “arm64”)
  2. PREFERRED_PROVIDER_virtual/kernel
  3. MACHINE_FEATURES (e.g. “pci wifi bluetooth”)
  4. SERIAL_CONSOLES (e.g. “115200 ttymxc2”)
  5. KERNEL_IMAGETYPE (e.g. “uImage”)
  6. IMAGE_FSTYPES (e.g. “tar.gz sdcard.gz”)

Some of these variables get inherited from the NXP files:

conf/machine/include/imx-base.inc
conf/machine/include/arm/arch-arm64.inc

Adding a Boot Loader for the Machine

The OpenEmbedded build system needs to be able to build a boot loader for the machine.
You need to either create a new boot loader recipe for this machine, or extend an existing boot loader recipe.

Extending existing recipe

FILESEXTRAPATHS_prepend := "${THISDIR}/compulab/imx8mq:"

include compulab/imx8mq.inc

SRC_URI_append += " \
	https://github.com/compulab-yokneam/logos/raw/master/300x153x8bit/compulab.bmp;protocol=https;md5sum=da59211e201bfcecc53483a0a5c025f1;sha256sum=0a447cc174ca16236ac46c290d6c177cd6be9fc1ad96749c1784d0504522fb47 \
"

do_configure_append_cl-som-imx8 () {
	cp -rfv ${WORKDIR}/compulab.bmp ${S}/tools/logos/
}

PACKAGE_ARCH = "${MACHINE_ARCH}"
COMPATIBLE_MACHINE = "(cl-som-imx8)"

Adding a Kernel for the Machine

The OpenEmbedded build system needs to be able to build a kernel for the machine.
You need to either create a new kernel recipe for this machine, or extend an existing kernel recipe.

Creating new recipe

SUMMARY = "CompuLab Linux Kernel"
DESCRIPTION = "CompuLab Linux Kernel"

require recipes-kernel/linux/linux-imx.inc
require recipes-kernel/linux/linux-imx-src-${PV}.inc

DEPENDS += "lzop-native bc-native"

FILESEXTRAPATHS_prepend := "${THISDIR}/compulab/imx8mq:"
include compulab/imx8mq.inc

do_configure_append () {
    oe_runmake ${MACHINE}_defconfig
}

KERNEL_MODULE_AUTOLOAD += "goodix"
KERNEL_MODULE_AUTOLOAD += "snd_soc_wm8731"

COMPATIBLE_MACHINE = "cl-som-imx8"

In order to use this approach the conf/local.conf file must have this PREFERRED_PROVIDER_virtual/kernel value:

PREFERRED_PROVIDER_virtual/kernel_cl-som-imx8 = "linux-compulab"

Extending existing recipe

FILESEXTRAPATHS_prepend := "${THISDIR}/compulab/imx8mq:"

include compulab/imx8mq.inc

do_configure_append () {
    oe_runmake ${MACHINE}_defconfig
}

KERNEL_MODULE_AUTOLOAD += "goodix"
KERNEL_MODULE_AUTOLOAD += "snd_soc_wm8731"

COMPATIBLE_MACHINE = "(cl-som-imx8)"

CompuLab Meta Layer Example

Admolition note.png See below a example of the meta-layer's directory tree

See for the meta-bsp-imx8mq source files in GitHub.

The layer folder in built of a few files and directories:

  • conf/layer.con - the layer configuration files
  • conf/machine/cl-som-imx8.conf - the machine configuration files
  • recipes-bsp/u-boot/u-boot-imx_2018.03.bbappend - U-Boot recipe extension of the NXP meta-fsl-bsp-release/imx/meta-bsp/recipes-bsp/u-boot/u-boot-imx_2018.03.bb
  • recipes-kernel/linux/linux-imx_4.14.%.bbappend - Kernel recipe extension of the NXP meta-fsl-bsp-release/imx/meta-bsp/recipes-kernel/linux/linux-imx_4.14.98.bb
  • recipes-bsp and recipes-kernel, each containing the recipes for the appropriate software part, here specifically for the compulab imx8mq.
  • for each of the above, we have :
    • a directory containing the patch files
    • an imx8mq.inc listing the patch files names
    • one or more *.bbappend files containing the actions to taken in addition ("appended")

CompuLab meta-bsp-imx8mq meta-layer directory tree

.
├── conf
│   ├── layer.conf
│   └── machine
│       └── cl-som-imx8.conf
├── recipes-bsp
│   └── u-boot
│       ├── compulab
│       │   ├── imx8mq
│       │   │   ├── 0000-cl-som-imx8-Add-board-support.patch
│       │   │   ├── 0001-cl-som-imx8-Remove-unused-firmware.patch
│       │   │   ├── 0002-cl-som-imx8-Add-usb-support.patch
│       │   │   ├── 0003-cl-som-imx8-Update-Android-support.patch
│       │   │   ├── 0004-cl-som-imx8-Fix-usb-support.patch
│       │   │   ├── 0005-cl-som-imx8-Update-memory-init-code.patch
│       │   │   ├── 0006-cl-som-imx8-pmic-Increase-GPU-power-rail-voltage.patch
│       │   │   ├── 0007-cl-som-imx8-pmic-Increase-DRAM-power-rail-voltage.patch
│       │   │   ├── 0008-cl-som-imx8-Add-board-cfg-GPIO-for-RAM-size.patch
│       │   │   ├── 0009-cl-som-imx8-Refactoring-RAM-configuration.patch
│       │   │   ├── 0010-cl-som-imx8-config-RAM_BOARD_CFG-is-the-default.patch
│       │   │   ├── 0011-cl-som-imx8-defconfig-Enable-USB-ethernet.patch
│       │   │   ├── 0012-cl-som-imx8-defconfig-Add-rev-to-LOCAL_VERSION.patch
│       │   │   ├── 0013-cl-som-imx8-defconfig-Add-d1-d2-configs.patch
│       │   │   ├── 0014-cl-som-imx8-defconfig-Enable-OPTEE.patch
│       │   │   ├── 0015-cl-som-imx8-defconfig-Disable-TMU.patch
│       │   │   ├── 0016-CL-SOM-iMX8-Enable-LED.patch
│       │   │   ├── 0017-Enable-eeprom-cmd.patch
│       │   │   └── cl-som-imx8_defconfig
│       │   └── imx8mq.inc
│       └── u-boot-imx_2018.03.bbappend
└── recipes-kernel
    └── linux
        ├── compulab
        │   ├── imx8mq
        │   │   ├── 0000-cl-som-imx8-Add-CompuLab-device-tree-files.patch
        │   │   ├── 0001-cl-som-imx8-config-Add-defconfig.patch
        │   │   ├── 0002-cl-som-imx8-Add-SoM-driver.patch
        │   │   ├── 0003-sn65dsi83-Add-dsi2lvds-bridge.patch
        │   │   ├── 0004-ov5640_mipi_v2-gpio-can-sleep.patch
        │   │   ├── 0005-cl-som-imx8-dtb-Update-Makefile.patch
        │   │   ├── 0006-cl-som-imx8-Simple-Sound-Support.patch
        │   │   ├── 0007-cl-som-imx8-dts-Device-tree-refactoring.patch
        │   │   ├── 0008-cl-som-imx8-defconfig-Update-defconfig.patch
        │   │   ├── 0009-cl-som-imx8-Fix-SD1_RESET.patch
        │   │   ├── 0010-cl-som-imx8-defconfig-FRAMEBUFFER_CONSOLE_ROTATION-y.patch
        │   │   ├── 0011-cl-som-imx8-dts-Add-a-non-edid-dts-file.patch
        │   │   ├── 0012-imx-hdp-Added-user-defined-video-modes.patch
        │   │   ├── 0013-cl-som-imx8-sb-Add-hubpwren-regulator.patch
        │   │   ├── 0014-cl-som-imx8-defconfig-Update-defconfig.patch
        │   │   ├── 0015-cl-som-imx8-defconfig-Enable-wm8731-with-sdma-as-a-m.patch
        │   │   ├── 0016-cl-som-imx8-Remove-unused-dvfs-regulator.patch
        │   │   ├── 0017-cl-som-imx8-rmpms-Removed-the-rpmsg-pingpong-area.patch
        │   │   ├── 0018-cl-som-imx8-dts-m4-Added-sbc-imx8-m4-file.patch
        │   │   ├── 0019-cl-som-imx8-dts-Change-mipi-dcss-clock-settings.patch
        │   │   ├── 0020-cl-som-imx8-defconfig-Update-config.patch
        │   │   ├── 0021-cl-som-imx8-dts-Fix-the-csi-assigned-clock-rate.patch
        │   │   ├── 0022-cl-som-imx8-dts-Changed-sn65dsi83-clock-to-a-support.patch
        │   │   ├── 0023-cl-som-imx8-dts-Fix-the-dcss-assigned-clocks.patch
        │   │   ├── 0024-cl-som-imx8-dts-Increase-lcdif-max-res-to-1920x1200.patch
        │   │   └── defconfig
        │   └── imx8mq.inc
        └── linux-imx_4.14.%.bbappend