Real-time system observability for Zephyr RTOS, delivered over SWD.

Stop guessing your stack margins and heap health. ZView provides a zero-footprint, high-fidelity visualization of your Zephyr application’s runtime, delivered over SWD with zero instrumentation.

No UART, no RTT, and no manual code changes. Just Kconfig and your probe.

Looking for the standalone pip installation? See README_pip.md.

To properly analyze your Zephyr app, your ELF binary must be compiled with specific Kconfig options enabled:

## prj.conf
CONFIG_INIT_STACKS=y            # Required for stack watermarks
CONFIG_THREAD_MONITOR=y         # Required for thread discovery
CONFIG_THREAD_STACK_INFO=y      # Required for thread metadata

# Optional Features
CONFIG_THREAD_NAME=y            # Enables thread name display
CONFIG_THREAD_RUNTIME_STATS=y   # Enables CPU usage tracking
CONFIG_SYS_HEAP_RUNTIME_STATS=y # Enables heap runtime stats and fragmentation map

Add this snippet to your west manifest:

manifest:
  projects:
    - name: zview
      url: https://github.com/wkhadgar/zview
      revision: main
      path: modules/tools/zview
      west-commands: scripts/west-commands.yml

Then fetch it with:

west update zview

If your board is already flashed and probed, ZView can often infer the ELF path and runner from the build directory — just run:

# From project root
west zview

Or pass arguments explicitly:

# Example: nRF5340 DK via JLink
west zview -e build/zephyr/zephyr.elf -r jlink -t nRF5340_xxAA

ZView is invoked through one of four commands. Bare zview ... is a shortcut for zview live ....

# Example: Nordic nRF5340 DK
west zview -e build/zephyr/zephyr.elf -r jlink -t nRF5340_xxAA

pyocd list --targets          # find your target name

# Example: STM32F401 Nucleo
west zview -e build/zephyr/zephyr.elf -r pyocd -t stm32f401xe

west zview -e build/zephyr/zephyr.elf -r gdb -t localhost:1234

ZView acts as a TUI. Navigate with UP and DOWN arrows from the default view:

• ENTER: Get details for a specific thread/heap (hit ENTER again to return).
• S / I: Sort the data and invert the sorting order.
• H: Access the Heap Runtime visualization (hit H again to return).

ZView can record a live session to disk, replay it later without a probe, or emit a single frame as JSON for CI.

Record a live session:

# 30 s of live polling from a JLink probe, saved to disk
west zview record -e build/zephyr/zephyr.elf -r jlink -t nRF5340_xxAA \
  -o capture.ndjson.gz --duration 30

Bound the recording by either --duration (seconds) or --frames (number of data frames).

To also capture the fragmentation map for a specific heap, pass --heap <name> where <name> matches a k_heap variable from your firmware (e.g. my_kernel_heap):

west zview record -e build/zephyr/zephyr.elf -r jlink -t nRF5340_xxAA \
  -o capture.ndjson.gz --duration 30 --heap my_kernel_heap

Replay it later — no hardware needed:

# Feed the recording into the TUI
west zview replay -e build/zephyr/zephyr.elf -i capture.ndjson.gz

By default the replay honors the recording's original cadence. Pass --no-pacing to drain it as fast as possible.

The ELF is still required: DWARF offsets are resolved at replay time and are not stored in the recording.

CI-friendly single-frame snapshot:

# One polling frame from a live probe, dumped as JSON on stdout
west zview dump -e build/zephyr/zephyr.elf -r jlink -t nRF5340_xxAA --json \
  | jq '.threads[] | select(.runtime.stack_watermark_percent > 80)'

dump accepts either a live source (-r/-t) or a recording (-i). Omit --json for a human-readable one-shot dump. Use --frame N to emit the Nth polling frame instead of the first — useful when the first frame's CPU baseline hasn't settled.

Note: Status messages (probe connect, ELF load) are emitted on stderr, so stdout stays clean for piping into jq or similar.

west debugserver

qemu-system-arm \
  -machine mps2-an385 \
  -cpu cortex-m3 \
  -kernel build/zephyr/zephyr.elf \
  -nographic \
  -serial mon:stdio \
  -s

west zview -r gdb -t localhost:1234

Feel free to open an issue if you feel like this has some potential!