I recently ran into a SNAFU when trying to build a PetaLinux image for a PicoZed board on a rev 2 FMC carrier board. The instructions assume that you have built an FPGA image and exported it from Vivado. You can check out my tutorial on PetaLinux for more background information, just in case you’re unfamiliar with the process.

You’re going to need to make sure that you have the board support package for the PicoZed board and carrier board you are using, which can download here. I like to keep the BSP in my Xilinx tool area, but you can store it anywhere you like. Be sure to unzip the download file.

Create the project

First, I source the settings file for PetaLinux. Don’t worry about the tftp warnings.

% . /tools/xilinx/petalinux-v2015.4-final/settings.sh

Now create your PetaLinux project. I created it as a sibling of the Vivado project directory.

% petalinux-create --type project --name pz_linux --source /tools/xilinx/pz_7015_2015_4.bsp

Configure the project

Next, you configure the project with the FPGA export. This sets the device tree for the build:

% petalinux-config --get-hw-description my_fpga/my_fpga.sdk --project pz_linux

Then, configure your filesystem:

% petalinux-config -c rootfs --project pz_linux

PetaLinux build fails

If we run petalinux-build right now, we run in to some trouble:

% petalinux-build --project pz_linux
INFO: Checking component...
INFO: Generating make files and build linux
INFO: Generating make files for the subcomponents of linux
INFO: Building linux
[INFO ] pre-build linux/rootfs/fwupgrade
[INFO ] pre-build linux/rootfs/gpio-demo
[INFO ] pre-build linux/rootfs/httpd_content
[INFO ] pre-build linux/rootfs/iperf3
[INFO ] pre-build linux/rootfs/peekpoke
[INFO ] pre-build linux/rootfs/weaved
[INFO ] build system.dtb
[ERROR] ERROR (phandle_references): Reference to non-existent node or label "usb_phy0"
[ERROR] ERROR: Input tree has errors, aborting (use -f to force output)
[ERROR] make[1]: *** [system.dtb] Error 255
ERROR: Failed to build linux

Fixing the device tree

The problem is that the device tree was overwritten by the petalinux-config. To fix that, we need to add the following lines to the system-conf.dtsi file located in pz_linux/subsystems/linux/configs/device-tree. Place the text following the entry for memory:

usb_phy0:phy0 {
  compatible="ulpi-phy";
  #phy-cells = ;
  reg = ;
  view-port = ;
  drv-vbus;
};

With this change in place, we can go ahead and run petalinix-build again, and the build will complete. I’m not exactly sure why this procedure is required or how to patch the PetaLinux install to fix this. I will explore that later.

Packaging

After building, you will need to package the distribution.

% petalinux-package --boot --format BIN --project pz_linux --fsbl pz_linux/images/linux/zynq_fsbl.elf --fpga my_fpga/impl_1/my_fpga.bit --u-boot

Copy the BOOT.BIN and pz_linux/images/linux/image.ub files to your MicroSD care and boot your PicoZed board.

Let me know if you have any ideas why this problem exists or how you can fix it.