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:

• files for rootfs in NAND Flash: poky/build/tmp/deploy/images/elphel393/nand/
• files for rootfs on MMC (micro SD card): poky/build/tmp/deploy/images/elphel393/mmc/

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 listed interfaces, zynq registers, interrupts and drivers
• uImage - kernel, drivers
• rootfs.ubifs or rootfs.tar.gz - rootfs

Boot options

Boot from micro SD card (rootfs)

• The micro SD card/adapter must be modified for this boot mode (to keep CD pin high) - only then the camera will boot
• EXT4 partition mounted as /
• Detailed instructions

Boot from NAND flash (rootfs)

• The default boot option - power on.
• A UBIFS image is written to /dev/mtd4 - is mounted as /
• Detailed instructions

Notes

• It is possible to unpack rootfs to RAM not mounting any partitions (/ in RAM, ramdisk):
  • Changes are not stored
  • Boot faster?
  • Work faster?
  • Modify env commands in the u-boot (in elphel393.h or when in the u-boot command line)
  • Carefully check the actual and hardcoded images' sizes in the u-boot (elphel393.h) and the device tree (elphel393_xxx.dts) with the actual sizes.

Setup

$ git clone https://github.com/Elphel/elphel393.git
$ cd elphel393
$ ./setup.sh
$ cd poky
$ . ./oe-init-build-env
$ bitbake u-boot 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