Poky manual

Description

• Building embedded Linux image for Zynq ARMv7 platform - Elphel 10393 board

About

• Yocto Poky revision = 2.0
• Host OS = Kubuntu 14.04.3 LTS x64

Required packages

• Found in Yocto Project mega-manual

Output files

Found in the poky's deploy directory: poky/build/tmp/deploy/images/

These names are listed as they appear in the u-boot configuration header file - actual output files have different names:

• boot.bin - u-boot as the first stage bootloader = Secondary Program Loader that boots u-boot-dtb.img
• u-boot-dtb.img - full size u-boot with a stripped device tree (cat u-boot.img some_stripped_devicetree.dtb > u-boot-dtb.img)
• devicetree.dtb - device tree with described interfaces, zynq registers, interrupts and drivers
• uImage - kernel, drivers
• uramdisk.image.gz - applications

Copy them on the micro SD card (FAT partition) > run boot once in the u-boot command line.

Boot options

• Auto unpacking the root file system image to RAM when booting:
  • Check u-boot default environment variables when building the bootloader.
  • Keep uramdisk.image.gz along with all the other files on the FAT partition of (micro)SD card.
• Root file system on EXT2(EXT3,etc.) partition of (micro)SD card.

Setup

• Step 1: Copy the following lines to some_script.sh, modify and run:

#Part 1

git clone -b master git://git.yoctoproject.org/poky.git poky
cd poky; git checkout 3d2c0f5902cacf9d8544bf263b51ef0dd1a7218c
 
git clone -b master https://github.com/Elphel/meta-ezynq.git meta-ezynq
cd meta-ezynq; git checkout b8b1cd8e6dae7cadb51e987f966a4ffbcd6c6543; cd ..

git clone -b master https://github.com/Elphel/meta-elphel393.git meta-elphel393
cd meta-elphel393; git checkout c5237f99d94217bff8c9180bed93ee673c9590a1; cd ..

git clone -b master https://github.com/Xilinx/meta-xilinx.git meta-xilinx
cd meta-xilinx; git checkout cc146d6c170f100eb2f445047969893faa7a6a55; cd ..

git clone -b master git://git.openembedded.org/meta-openembedded meta-openembedded
cd meta-openembedded; git checkout 73854a05565b30a5ca146ac53959c679b27815aa; cd ..

#Part 2 : init environment and auto-fill Yocto's conf-files

CURRENT_PATH=$(dirname $(readlink -f "$0"))
. ./oe-init-build-env

BBLAYERS_CONF="conf/bblayers.conf"

echo "BBLAYERS = \" \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta-yocto \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta-yocto-bsp \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta-ezynq \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta-elphel393 \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta-xilinx \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta-openembedded/meta-oe \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta-openembedded/meta-python \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta-openembedded/meta-networking \\" >> $BBLAYERS_CONF
echo "  $CURRENT_PATH/meta-openembedded/meta-webserver \\" >> $BBLAYERS_CONF
echo "  \"" >> $BBLAYERS_CONF

LOCAL_CONF="conf/local.conf"

# change the MACHINE
echo "MACHINE ?= \"elphel393\"" >> $LOCAL_CONF
# Elphel's MIRROR website, \n is important
echo "MIRRORS =+ \"http://.*/.*     http://mirror.elphel.com/elphel393_mirror/ \n \"" >> $LOCAL_CONF

• Step 2: re-init environment

cd poky
. ./oe-init-build-env

• Step 3: build bootable image (3 targets)

bitbake u-boot-ezynq device-tree linux-xlnx core-image-elphel393

Build bootloader

bitbake u-boot-ezynq
or
bitbake u-boot
or
bitbake virtual/bootloader

Output

• poky/build/tmp/deploy/images/<machine>/boot.bin
• poky/build/tmp/deploy/images/<machine>/u-boot-dtb.img

Notes

• Since Poky 1.5.1 switched from u-boot-xlnx to u-boot - some of the u-boot-xlnx reached the upstream
• Since Poky 1.5.1 u-boot introduced Kconfig and currently (as of 2016/01/22) is still migrating from autoconf - keeping both build methods working together.
• Current u-boot uses the board's device tree blob to make a stripped version for itself - uncompiled device tree files are present in the u-boot sources

Compile devicetree

bitbake device-tree

Output

• poky/build/tmp/deploy/images/<machine>/devicetree.dtb

Build kernel

bitbake linux-xlnx
or
bitbake virtual/kernel

Output

• poky/build/tmp/deploy/images/<machine>/uImage (kernel)

Notes

• Kernel version is 4.0, linux-xlnx
• Device Tree Blob is compiled separately in linux-xlnx
• Uncompiled device tree files are present in the linux sources provided by linux-xlnx

Build ramdisk.image.gz

bitbake core-image-elphel393

Output

• poky/build/tmp/deploy/images/<machine>/uramdisk.image.gz (the file has *.u-boot extension after it's built)

Notes

• [FIXED] lighttpd-1.4.39, mod-cgi

compile warning:

implicit declaration of function 'chunkqueue_written'

results in lighttpd failing to start if mod-cgi is enabled:

Starting Lighttpd Web Server: 2016-01-26 18:42:17: (/data/GIT_fresh/poky/build/tmp/work/cortexa9-vfp-neon-poky-linux-gnueabi/lighttpd/1.4.36-r0/lighttpd-1.4.36/src/plugin.c.169) dlopen() failed for: /usr/lib/mod_cgi.so /usr/lib/mod_cgi.so: undefined symbol: chunkqueue_w 
2016-01-26 18:42:17: (/data/GIT_fresh/poky/build/tmp/work/cortexa9-vfp-neon-poky-linux-gnueabi/lighttpd/1.4.36-r0/lighttpd-1.4.36/src/server.c.679) loading plugins finally failed 
lighttpd.

Note: why 1.4.36?!!

solution: exclude the 0001-mod_cgi-buffers-data-without-bound.patch from the file list that comes with the poky/meta/recipes-extended/lighttpd_1.4.39.bb