Wednesday, July 15, 2015

Creating a custom Linux BSP for an ARM Cortex-A9 SBC with Yocto 1.8 - Part II

In the second part of this guide, the source code will be pulled, the build configuration will be customized, and the build will be executed.  Part II of this guide consists of the following sections.

  1. Pull the Freescale community BSP platform source code from github. 
  2. Setup the build environment using the predefined imx6dl-riotboard RioTboard (Internet of Things) machine.
  3. Create a new layer for the custom Linux distribution.
  4. Customize the image in the meta-bsec layer. 
  5. Create layer.conf file in the meta-bsec layer. 
  6. Create the distribution configuration file in the meta-bsec layer. 
  7. Add the new layer to bblayers.conf.
  8. Customize the local configuration.
  9. Execute
    the build.

1. Pull the Freescale community BSP platform source code from github.


Execute the following commands on the host.
 host]$ mkdir $HOME/bin  
host]$ curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
host]$ chmod a+x $HOME/bin/repo
host]$ echo "PATH=$PATH:$HOME/bin" >> $HOME/.bashrc
host]$ source .bashrc
host]$ mkdir -p $HOME/src/fsl-community-bsp
host]$ cd $HOME/src/fsl-community-bsp
host]$ repo init -u https://github.com/Freescale/fsl-community-bsp-platform -b fido
host]$ repo sync

2. Setup the build environment using the predefined imx6dl-riotboard machine.


Execute the following commands on the host.

 host]$ MACHINE=imx6dl-riotboard . ./setup-environment build  

3. Create a new layer for the custom Linux distribution


Execute the following commands on the host.

 host]$ cd $HOME/src/fsl-community-bsp/sources  
host]$ mkdir -p meta-bsec/conf/distro
host]$ mkdir -p meta-bsec/recipes-bsec/images
host]$ cd poky/meta/recipes-extended/images
host]$ cp core-image-full-cmdline.bb \
../../../../meta-bsec/recipes-bsec/images/bsec-image.bb

4. Customize the image in the meta-bsec layer.


Execute the following commands on the host.

  host]$ cd $HOME/src/fsl-community-bsp/sources/meta-bsec/recipes-bsec/images

Customize bsec-image.bb as follows.  Lines with bold text indicate lines to add to the file.

 DESCRIPTION = "A console-only image with more full-featured Linux system \
functionality installed."

# customize IMAGE_FEATURES as follows
IMAGE_FEATURES += "dev-pkgs tools-sdk tools-debug tools-profile tools-testapps \
debug-tweaks splash ssh-server-openssh package-management"

# packagegroup-core-tools-profile will build and install tracing and profiling tools to the target image.
# packagegroup-core-buildessential will build and install autotools, gcc, etc. to the target image.
# kernel-modules for install of the kernel modules.
# kernel-devsrc for building out of tree modules.
# IMAGE_ROOTFS_EXTRA_SPACE_append for adding extra space to the target rootfs image.

# customize IMAGE_INSTALL as follows
IMAGE_INSTALL = "\
packagegroup-core-boot \
packagegroup-core-full-cmdline \
packagegroup-core-tools-profile \
packagegroup-core-buildessential \
kernel-modules \
${CORE_IMAGE_EXTRA_INSTALL} \
kernel-devsrc \
"
inherit core-image

# Add extra space to the rootfs image
IMAGE_ROOTFS_EXTRA_SPACE_append += "+ 3000000"

5. Create layer.conf file in the meta-bsec layer.


Create sources/meta-bsec/conf/layer.conf with the below contents.

BBPATH .= ":${LAYERDIR}"  
BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
${LAYERDIR}/recipes-*/*/*.bbappend"
BBFILE_COLLECTIONS += "bsec"
BBFILE_PATTERN_bsec = "^${LAYERDIR}/"
BBFILE_PRIORITY_bsec = "6"


6. Create the distribution configuration file in the meta-bsec layer.


Create sources/meta-bsec/conf/disro/bsecdist.conf with the below contents.

 require conf/distro/poky.conf    
# distro name
DISTRO = "bsecdist"
DISTRO_NAME = "bsecdist distribution"
DISTRO_VERSION = "1.0"
DISTRO_CODENAME = "bsc"
DISTRO_FEATURES_append = " alsa usbhost usbgadget keyboard bluetooth"
SDK_VENDOR = "-bsecdistsdk"
SDK_VERSION := "${@'${DISTRO_VERSION}'.replace('snapshot-${DATE}','snapshot')}"
MAINTAINER = "bsecdist "
INHERIT += "buildhistory"
BUILDHISTORY_COMMIT = "1"

7. Add the new layer to bblayers.conf


Execute the following commands on the host.

 host]$ cd $HOME/src/fsl-community-bsp/build/conf

Customize bblayers.conf by adding the meta-bsec layer to BBLAYERS as follows.

 LCONF_VERSION = "6"

BBPATH = "${TOPDIR}"
BSPDIR := "${@os.path.abspath(os.path.dirname(d.getVar('FILE', True)) + '/../..')}"

BBFILES ?= ""
BBLAYERS = " \
${BSPDIR}/sources/poky/meta \
${BSPDIR}/sources/poky/meta-yocto \
\
${BSPDIR}/sources/meta-openembedded/meta-oe \
${BSPDIR}/sources/meta-openembedded/meta-multimedia \
\
${BSPDIR}/sources/meta-fsl-arm \
${BSPDIR}/sources/meta-fsl-arm-extra \
${BSPDIR}/sources/meta-fsl-demos \
${BSPDIR}/sources/meta-bsec \
"

8. Customize the local configuration


Customize local.conf as follows.

 MACHINE ??= 'imx6dl-riotboard'
# set distro name
DISTRO ?= 'bsecdist'
PACKAGE_CLASSES ?= "package_rpm package_deb"
EXTRA_IMAGE_FEATURES = " "
USER_CLASSES ?= "buildstats image-mklibs image-prelink"
PATCHRESOLVE = "noop"
BB_DISKMON_DIRS = "\
STOPTASKS,${TMPDIR},1G,100K \
STOPTASKS,${DL_DIR},1G,100K \
STOPTASKS,${SSTATE_DIR},1G,100K \
ABORT,${TMPDIR},100M,1K \
ABORT,${DL_DIR},100M,1K \
ABORT,${SSTATE_DIR},100M,1K"
PACKAGECONFIG_append_pn-qemu-native = " sdl"
PACKAGECONFIG_append_pn-nativesdk-qemu = " sdl"
ASSUME_PROVIDED += "libsdl-native"
CONF_VERSION = "1"
BB_NUMBER_THREADS = '4'
PARALLEL_MAKE = '-j 4'
DL_DIR ?= "${BSPDIR}/downloads/"
ACCEPT_FSL_EULA = "1"
# archive source code for all of the packages that will be built into the image
INHERIT += "archiver"
ARCHIVER_MODE[src] = "original"
# ensure that license files accompany each binary in final image
COPY_LIC_MANIFEST = "1"
COPY_LIC_DIRS = "1"
# setup source mirror
# make sure that bitbake checks for all of the source tarballs in a local directory
# before going to the Internet to fetch them.
SOURCE_MIRROR_URL ?= "file://${BSPDIR}/source-mirror/"
INHERIT += "own-mirrors"
# create a shareable cache of source code management backends
BB_GENERATE_MIRROR_TARBALLS = "1"

9. Execute the build


Execute the following commands on the host.

 host]$ cd $HOME/src/fsl-community-bsp/build 
host]$ time bitbake bsec-image

While the image is building, please take note of the following.

The input specifications for the GNU/Linux kernel and U-boot segments of the BSP are in the below files. These specifications include such things as GNU/Linux kernel patch files for i.MX 6 processor features, kernel boot args, kernel load address, cortex specific tuning parameters, etc.

 sources/meta-fsl-arm-extra/conf/machine/imx6dl-riotboard.conf  
sources/poky/meta-yocto/conf/distro/poky.conf
sources/meta-fsl-arm/recipes-kernel/linux/linux-imx.inc
sources/meta-fsl-arm/recipes-kernel/linux/linux-fslc_4_0.bb
sources/poky/meta/conf/machine/include/tune-cortexa9.inc

In part III of this guide, the image will be booted on the target and then audio will be tested, including recording and playback. Continue to part III of this guide.

Continue to Part III

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