Advanced: project structure and customization

This section is intended for users who want to modify the reference designs — adding IP to the block design, changing constraints, modifying the standalone application, or adding packages or drivers to the PetaLinux project. It describes how the repository is laid out, how the build flow works, how the Vitis and PetaLinux sides are organised, and what modifications have been added on top of the stock AMD BSPs.

The actual build instructions are in build_instructions; this section is about understanding the project well enough to modify it.

Repository layout

.
├── build.py                   <- Cross-platform build runner (the build logic)
├── build.sh / build.bat       <- Shims that invoke build.py (Linux/git bash, Windows)
├── Makefile                   <- Deprecated thin wrapper around build.sh (removed next version)
├── README.md
├── config/                    <- Source-of-truth design metadata and auto-generation
│   ├── data.json
│   └── update.py
├── docs/                      <- This documentation (Sphinx + Read the Docs)
├── PetaLinux/
│   └── bsp/                   <- Per-board (and optional per-target) BSP fragments
│       └── pynqzu/, uzev/, zcu102/, zcu102_hpc1/, zcu104/, zcu106/
├── submodules/                <- Vendor board definition files (BDFs)
├── Vivado/
│   ├── scripts/
│   │   ├── build.tcl          <- Project creation + block design assembly
│   │   └── xsa.tcl            <- Synthesis, implementation, XSA export
│   └── src/
│       ├── bd/
│       │   ├── bd_mb.tcl      <- Block design for MicroBlaze targets
│       │   ├── bd_zynqmp.tcl  <- Block design for Zynq UltraScale+ targets
│       │   └── mipi_locs.tcl  <- Per-target MIPI lane placement constants
│       └── constraints/
│           └── <target>.xdc   <- One XDC per target (pin assignments, timing)
└── Vitis/
    ├── py/
    │   ├── args.json          <- Repo-specific Vitis flow configuration
    │   ├── build-vitis.py     <- Universal Vitis Python build driver
    │   └── make-boot.py       <- BOOT.BIN packaging
    ├── common/
    │   └── src/               <- Standalone application source (camera bring-up)
    └── <target>_workspace/    <- Per-target Vitis workspace (generated)

Per-target build outputs are written to Vivado/<target>/, Vitis/<target>_workspace/, and PetaLinux/<target>/; packaged boot-image zips are written to bootimages/. None of these are committed.

There is no port-config overlay in this repository — there is at most one Raspberry Pi camera array per design, and per-target customisation is done via per-target BSP overlays where needed (see PetaLinux side below).

Target naming

A target label is the canonical handle for a single design and is passed to every build command via --target. It encodes the board and, for boards with multiple FMC connectors, the connector:

<board>[_<connector>]

Examples: uzev, zcu102_hpc0, zcu102_hpc1, zcu104, pynqzu, auboard, genesyszu. The first underscore-delimited token is taken as the target board and is what the build runner uses to select the BSP under PetaLinux/bsp/<board>/.

The complete list of valid targets comes from config/data.json; run ./build.sh list (or ./build.sh labels for one per line) to print it.

config/data.json and config/update.py

config/data.json is the canonical source of truth for the set of supported designs and their per-target metadata (board name, processor family, FMC connector, baremetal-vs-PetaLinux support, etc.). The build.py runner reads it directly at runtime, so the target list is never hand-maintained.

config/update.py reads data.json and regenerates the auto-managed documentation and metadata that is not read at runtime: the target tables in the top-level README.md, the .gitignore, and the per-board sections still embedded in PetaLinux/Makefile — each delimited by UPDATER START / UPDATER END comment markers.

When adding or modifying a target, edit data.json and re-run update.py. Do not hand-edit content between the UPDATER START / UPDATER END markers; it will be overwritten on the next regeneration.

Build runner

All build stages are driven by the cross-platform build.py runner at the root of the repository, invoked through the build.sh shim on Linux / git bash or build.bat on Windows (identical arguments). It reads the target list and per-target attributes straight from config/data.json, builds whatever a requested stage depends on automatically, skips anything already built, and locates and sources the AMD tools itself — so there is no need to source the Vivado / Vitis / PetaLinux settings scripts beforehand.

The build is organised into stages, each available as a sub-command:

Command

Stage

project

Create the Vivado project (.xpr) and block design.

xsa

Synthesise, implement and export the hardware (.xsa).

standalone

Create the Vitis workspace, build the baremetal app, package BOOT.BIN / .mcs.

petalinux

Create the PetaLinux project from the XSA, apply the BSP overlays, build and package.

package

Gather the built boot artifacts into bootimages/*.zip.

all

Build every stage the target supports, then package.

Run ./build.sh list to see the targets and their attributes, ./build.sh status --target <t> for per-stage artifact state, and ./build.sh --help for the full command list.

Each target is flagged in config/data.json for the stages it supports — the MicroBlaze target (auboard) is baremetal-only (no PetaLinux), while the ZynqMP targets support the PetaLinux flow as well. Because each stage builds its prerequisites first, a single ./build.sh all --target <t> cascades the whole pipeline:

./build.sh all --target t
  -> xsa         : vivado creates the project (build.tcl), then synth/impl/XSA export (xsa.tcl)
  -> standalone  : vitis builds the platform + app, packages BOOT.BIN / .mcs
  -> petalinux   : petalinux-create -> -config --get-hw-description <XSA>
                   -> copy bsp/<board>/project-spec/* (and bsp/<target>/project-spec/* if present)
                   -> petalinux-build -> petalinux-package
  -> package     : zip the boot files into bootimages/

Build a single stage on its own with ./build.sh <stage> --target <t>; the runner still builds any missing prerequisite stages first.

Per-target lock files (.<target>.lock at the repository root) prevent two concurrent builds of the same target from clobbering each other — so two terminals can safely both run ./build.sh all --target all.

Vivado side

Block design

The block-design scripts live under Vivado/src/bd/:

  • bd_mb.tcl — MicroBlaze targets (auboard).

  • bd_zynqmp.tcl — Zynq UltraScale+ targets.

  • mipi_locs.tcl — Tcl dictionary mapping each target to its MIPI lane placement, sourced by the family scripts.

Each family script contains per-board conditional blocks where a target needs to deviate from the family defaults — typically for clock routing, PS configuration, or PL pinout.

After sourcing the BD script, scripts/build.tcl runs validate_bd_design -force, which triggers parameter propagation and fills in connection-automation rules. As a result the final implemented design may contain nets that aren’t visible in the BD TCL source — to see the actual netlist as built, inspect the saved .bd file under Vivado/<target>/<target>.srcs/sources_1/bd/<bd_name>/ or use write_bd_tcl to export a complete script from an open project.

Constraints

Vivado/src/constraints/<target>.xdc contains pin assignments and any target-specific timing constraints. Constraints common to all targets of a given family are not factored out — each target’s XDC is self-contained.

Build scripts

  • Vivado/scripts/build.tcl creates the Vivado project, adds the target’s XDC, sources the appropriate bd_*.tcl, and validates the block design. Invoked via ./build.sh project --target <t>.

  • Vivado/scripts/xsa.tcl opens the existing project, runs synthesis and implementation, exports the XSA, and writes the bitstream into the implementation run directory. Invoked via ./build.sh xsa --target <t>.

Both scripts check XILINX_VIVADO to confirm the installed Vivado version matches the version_required constant at the top of the file.

Modifying the block design

Edit the block-design script for the appropriate processor family directly. If the change applies only to some targets in the family, wrap the additions in the appropriate per-board conditional block.

Once the script is edited, delete any existing per-target Vivado project directory (rm -rf Vivado/<target>) and re-run the Vivado build:

./build.sh xsa --target <target>

This re-creates the project, sources the modified BD script, runs validate_bd_design, synthesises, implements, and re-exports the XSA. Downstream Vitis / PetaLinux / boot-image steps will pick up the new XSA on the next build.

Adding or modifying constraints

Edit Vivado/src/constraints/<target>.xdc directly. If a constraint applies to all targets in a family, it still needs to be replicated to each target’s XDC.

Vitis side

The standalone (baremetal) build is a camera bring-up application — it programmes the on-FMC clock generator (IDT 8T49N24x), the HDMI-out re-driver (DP159), the camera sensor (IMX219 / OV5640), the frame-buffer IP, and the HDMI pipeline. The source files in Vitis/common/src/ are grouped by device:

File pair

Purpose

i2c.[ch]

Generic I²C helpers

idt_8t49n24x.[ch]

Clock-generator programming

dp159.[ch]

HDMI re-driver programming

imx219.[ch]

Raspberry Pi v2 camera sensor

ov5640.[ch]

OmniVision sensor variant

rpi_cam.[ch]

High-level camera initialisation

pipe.[ch]

Video-pipeline setup

frmbuf.[ch]

Frame-buffer IP control

xhdmi_edid.[ch]

HDMI EDID handling

xhdmiphy1*.h

HDMI PHY register definitions

reset_gpio.h

GPIO reset macros

platform*.[ch], main.c

Platform glue and entry point

config.h

Build-time configuration switches

Layout

Vitis/
├── py/
│   ├── args.json
│   ├── build-vitis.py        <- Universal Vitis Python build driver
│   └── make-boot.py          <- BOOT.BIN / .mcs packaging
├── common/
│   └── src/                  <- Application source (see table above)
├── boot/<target>/            <- Per-target packaged boot files
└── <target>_workspace/       <- Generated Vitis workspace per target

args.json

Key fields:

  • bd_name — block-design name (rpi).

  • app_name — name of the Vitis application (test_app).

  • app_template — "None": the build driver creates an empty application project and adds source files explicitly rather than scaffolding from a Vitis template.

  • src — "all": "common/src".

  • combine_bit_elf — false.

  • stack_size / heap_size — 0x10000 each, raised from the defaults so the camera-bring-up code has room.

Modifying the standalone application

Edit Vitis/common/src/*.c (or .h) directly. The next ./build.sh standalone --target <t> rebuilds the application against the existing platform; if you’ve changed the hardware (XSA) you’ll need a fresh workspace (./build.sh clean --target <t> --stage standalone first).

PetaLinux side

BSP composition

The PetaLinux project for a given target is composed at build time from up to two BSP fragments copied into the target’s project directory:

  1. A board BSP at PetaLinux/bsp/<board>/ — always applied. Provides board-specific kernel and U-Boot configuration, the system device-tree fragment for the board, the initcams startup scripts (recipes-apps/initcams/), and any board-specific patches.

  2. An optional per-target BSP overlay at PetaLinux/bsp/<target>/ — applied only if the directory exists (the cp is prefixed with - in the Makefile so a missing directory is not an error). Currently zcu102_hpc1/ is the only such overlay, used to override the base zcu102/ BSP for the zcu102_hpc1 target.

There is no port-config overlay here; the structure of the imaging pipeline doesn’t vary per port the way the Ethernet-FMC ports do.

Layout of a board BSP

PetaLinux/bsp/<board>/project-spec/
├── configs/
│   ├── config                <- petalinux-config: bootargs, rootfs, hostname
│   ├── rootfs_config         <- petalinux-config -c rootfs: included packages
│   ├── init-ifupdown/
│   │   └── interfaces        <- /etc/network/interfaces
│   └── busybox/
│       └── inetd.conf
└── meta-user/
    ├── conf/
    │   ├── user-rootfsconfig <- declares additional rootfs config options
    │   ├── petalinuxbsp.conf
    │   └── layer.conf
    ├── recipes-apps/
    │   └── initcams/         <- Camera-init / display-camera shell scripts
    │       ├── initcams.bb
    │       └── files/
    │           ├── init_cams.sh
    │           └── displaycams.sh
    ├── recipes-bsp/
    │   ├── device-tree/
    │   │   ├── device-tree.bbappend
    │   │   └── files/
    │   │       └── system-user.dtsi    <- board-specific DT additions
    │   ├── u-boot/
    │   │   ├── u-boot-xlnx_%.bbappend
    │   │   └── files/
    │   │       ├── bsp.cfg
    │   │       ├── platform-top.h
    │   │       └── *.patch
    │   └── embeddedsw/                 <- (zcu104 only)
    │       ├── fsbl-firmware_%.bbappend
    │       └── files/
    │           └── zcu104_vadj_fsbl.patch
    ├── recipes-kernel/
    │   └── linux/
    │       ├── linux-xlnx_%.bbappend
    │       └── linux-xlnx/
    │           └── bsp.cfg             <- kernel Kconfig additions
    └── recipes-modules/                <- (pynqzu only)
        └── wilc/                       <- WiFi driver source patches

Adding a package to the root filesystem

  1. Append the new option to bsp/<board>/project-spec/configs/rootfs_config.

  2. If the package is not in the default petalinux-config -c rootfs menu, also append a declaration line to bsp/<board>/project-spec/meta-user/conf/user-rootfsconfig.

  3. If the package is not provided by an existing meta-layer, add a recipe under bsp/<board>/project-spec/meta-user/recipes-apps/<package>/<package>.bb.

Adding a kernel config option

Append the option to bsp/<board>/project-spec/meta-user/recipes-kernel/linux/linux-xlnx/bsp.cfg.

Adding a device-tree fragment

Edit bsp/<board>/project-spec/meta-user/recipes-bsp/device-tree/files/system-user.dtsi. If you add new files, ensure they are listed in SRC_URI:append in device-tree.bbappend.

Adding a kernel patch or out-of-tree driver

  1. Drop the patch file into bsp/<board>/project-spec/meta-user/recipes-kernel/linux/linux-xlnx/.

  2. Add SRC_URI:append = " file://<your-patch>.patch" to recipes-kernel/linux/linux-xlnx_%.bbappend.

For full out-of-tree modules, add a recipe under recipes-modules/<modname>/ (see bsp/pynqzu/.../recipes-modules/wilc/ as a working example — it builds the WILC WiFi driver and applies a PYNQ-ZU-specific patch).

Modifying U-Boot

The same pattern as the kernel, under bsp/<board>/project-spec/meta-user/recipes-bsp/u-boot/. bsp.cfg adds U-Boot Kconfig options; platform-top.h overrides the U-Boot platform header; patches are listed in SRC_URI:append in u-boot-xlnx_%.bbappend.

Modifications layered on the stock BSPs

The board BSPs in this repository started as the corresponding stock AMD reference BSPs and have been modified in the following ways. This list is the answer to “what would I lose if I overwrote the BSP with the stock one?” — it is what to re-apply if you ever do that.

All BSPs

Camera / userspace

  • Hostname / product name set in configs/config via CONFIG_SUBSYSTEM_HOSTNAME and CONFIG_SUBSYSTEM_PRODUCT.

  • SD-card root filesystem configured in configs/config: CONFIG_SUBSYSTEM_ROOTFS_EXT4, CONFIG_SUBSYSTEM_SDROOT_DEV, CONFIG_SUBSYSTEM_USER_CMDLINE (with cma= raised for the video frame buffers, and xlnx_mixer.connect_drm_bridge=1 to select the DRM-bridge code path in the Video Mixer driver — see kernel patches below).

  • Custom system-user.dtsi with device-tree nodes for the RPi-camera I²C bus, the camera sensors, the clock generator, and the frame-buffer / video pipeline.

  • recipes-apps/initcams/ providing the init_cams.sh and displaycams.sh startup scripts (init the cameras, bring up the display pipeline).

  • v4l-utils and yavta packages added to rootfs_config under the project customizations marker.

  • U-Boot patch 0001-ubifs-distroboot-support.patch.

2025.2 DP / Video Mixer pipeline fixes

In Vitis/PetaLinux 2025.2, the kernel DRM stack and the SDT BSP generator both got stricter in ways that break the v_mix → dpsub “live video” pipeline used by displaycams.sh. The following modifications are layered on every ZynqMP BSP in this repo to keep DP working. They are all gated to the v_mix DRM-bridge code path, so they are no-ops on any board that doesn’t use it.

  • Device-tree additions to system-user.dtsi:

    • Remove the auto-generated dp_port: port@0 block from inside &zynqmp_dpsub — the 2025.2 dpsub driver expects port endpoints inside the generated ports { … } subnode, not as a stray port@0 at the dpsub root.

    • Wire &live_video (port@0 of dpsub’s ports) endpoint to the v_mix CRTC port.

    • Wire &out_dp (port@5 of dpsub’s ports) endpoint to a new top-level dp-connector node — the driver requires some sink on the DP output side or it fails probe with DP output port not connected.

    • xlnx,bridge = <&display_pipeline_v_tc_0>; and xlnx,video-format = <2>; added to &display_pipeline_v_mix_0 — the 2025.2 xlnx-mixer driver requires both (otherwise probe fails with vtc bridge property not present / 'xlnx,video-format' property missing). The value 2 selects YUV422, which matches the NV16 primary layer.

  • Kernel patches in recipes-kernel/linux/linux-xlnx/, registered in linux-xlnx_%.bbappend:

    • 0001-drm-xlnx-mixer-fix-NULL-deref-in-connector_init.patch — fixes a kernel NULL deref at probe time in xlnx_mix_connector_init() and fixes shutdown-time use-after-free ordering by switching the encoder allocation from devm_kzalloc(&mixer->master->dev, …) (where mixer->master is NULL during bind) to drmm_kzalloc(mixer->drm, …), and from drm_simple_encoder_init() to drmm_encoder_init() (so the encoder cleanup is registered as a drm_managed action and runs in the right LIFO order during teardown).

    • 0002-drm-xlnx-drv-drop-mode_config_cleanup-on-unbind.patch — removes the manual drm_mode_config_cleanup(drm) call from xlnx_unbind(). The 2025.2 drm_bridge_connector_init() registers the connector via drm_managed, and calling drm_mode_config_cleanup manually before drm_dev_put causes a double cleanup of the connector (ida_free called for id=0 which is not allocated, then NULL deref in drm_connector_cleanup_action).

    • 0003-drm-xlnx-drv-disable-vblank-before-cleanup-on-shutdown.patch — adds drm_atomic_helper_shutdown(drm) at the start of xlnx_unbind() so vblank is disabled before drm_managed teardown runs. Without this, shutdown emits a non-fatal but noisy drm_WARN_ON(vblank->enabled && …) in drm_vblank_init_release.

  • xlnx_mixer.connect_drm_bridge=1 added to CONFIG_SUBSYSTEM_USER_CMDLINE. This kernel module parameter selects the new DRM-bridge code path in xlnx_mixer.c (the legacy path tries to look up the dpsub via xlnx,disp-bridge, but the 2025.2 dpsub no longer registers as an xlnx_bridge — so that lookup fails, the mixer’s encoder/connector never get set up, and modetest reports zero connectors).

ZCU104 BSP

  • FSBL patch zcu104_vadj_fsbl.patch in recipes-bsp/embeddedsw/files/, registered via fsbl-firmware_%.bbappend. The ZCU104 does not expose VADJ control to user logic, so the FSBL is patched to program the on-board IRPS5401 PMBus regulator to 1.8V before the FMC PHYs come out of reset.

  • 27 MHz dp_phy_refclk fixed-clock declared in system-user.dtsi, with &psgtr { clocks = <&dp_phy_refclk>; clock-names = "ref3"; }; overriding the auto-generated psgtr node. See ZCU106 BSP below for the rationale — this is the same fix.

ZCU106 BSP

  • 27 MHz dp_phy_refclk fixed-clock in system-user.dtsi, wired to &psgtr { clocks = <&dp_phy_refclk>; clock-names = "ref3"; };. The auto-generated pcw.dtsi enables &psgtr and tells the dpsub to consume refclk index 3 (xlnx,phys = <&psgtr X 6 X 3>), but does not declare any clocks on the psgtr node itself. As a result the 2025.2 psgtr driver’s xpsgtr_xlate() rejects refclk 3 at devm_phy_get time with Invalid reference clock number 3, and the dpsub fails to probe (failed to get PHY lane 0). Declaring a fixed-clock at the rate FSBL programs the on-board Si5341 to emit on the DP ref-clock pin (27 MHz) makes the psgtr driver’s SSC lookup succeed.

ZCU102 BSP

  • Used as the base BSP for both the zcu102_hpc0 target and (overlaid by bsp/zcu102_hpc1/) the zcu102_hpc1 target.

  • 27 MHz dp_phy_refclk fixed-clock in system-user.dtsi, same fix as documented under ZCU106 BSP. The ZCU102 has the same auto-generated psgtr-without-clocks problem and needs the same workaround.

UltraZed-EV (uzev) BSP

  • CONFIG_YOCTO_MACHINE_NAME="zynqmp-generic" in configs/config (the UZ-EV is not a stock Xilinx eval board).

  • SD-card device set to /dev/mmcblk1p2 rather than the ZynqMP default mmcblk0p2.

  • PRIMARY_SD_PSU_SD_1_SELECT=y to route the boot SD interface through PSU SD1 instead of SD0.

  • Custom system-user.dtsi with UZ-EV-specific peripheral configuration. Note: uzev already declares gtr_clk3 as a 27 MHz fixed-clock and assigns it to &psgtr clock-names = "ref3", so it does not need the dp_phy_refclk workaround that ZCU104 / ZCU106 / ZCU102 use — the dpsub probe succeeds on uzev out of the box.

PYNQ-ZU BSP

  • WILC WiFi driver overlay under recipes-modules/wilc/ with patch 0001-wilc-pynqzu.patch, adding support for the WILC1000 module fitted on the PYNQ-ZU carrier.

  • Like uzev, pynqzu already declares its DP refclk (dp_clk at “ref1”) in its own &psgtr { … } block, so it does not need the dp_phy_refclk fixed-clock workaround.

zcu102_hpc1 per-target overlay

  • Per-target BSP at bsp/zcu102_hpc1/ (in addition to the base bsp/zcu102/) that overrides device-tree nodes to wire the camera pipeline through the HPC1 connector instead of HPC0. All other modifications (kernel patches, cmdline, dpsub/v_mix dtsi fixes) come from bsp/zcu102/ unchanged via the Makefile’s two-stage cp -R bsp/$(TARGET_BOARD)/project-spec + cp -R bsp/$(TARGET)/project-spec.

Where build outputs land

Path

Contents

Vivado/<target>/

Vivado project. <bd_name>_wrapper.xsa is the export.

Vivado/<target>/<target>.runs/impl_1/<bd_name>_wrapper.bit

Bitstream.

Vivado/logs/

Per-target Vivado build logs.

Vitis/<target>_workspace/

Per-target Vitis workspace.

Vitis/boot/<target>/

Packaged Vitis boot files (BOOT.BIN for Zynq/ZynqMP, .mcs for MicroBlaze).

PetaLinux/<target>/

PetaLinux project. All Yocto build state lives here.

PetaLinux/<target>/images/linux/

BOOT.BIN, image.ub, boot.scr, rootfs.tar.gz, etc.

PetaLinux/<target>/build/build.log

PetaLinux build log.

bootimages/

Per-target zipped boot files.

None of these directories are committed to the repository.