Appendix — Userspace tooling reference

What this is. Throughout the book, chapters reach for bluetoothctl, nmcli, gst-launch-1.0, alsamixer, wpa_supplicant, i2c-tools, mosquitto-clients, tcpdump, iperf3, gpsd, chrony, libnfc, mtd-utils, gdbserver, … without saying where they come from. They come from whatever rootfs you built or chose. This appendix collects every tool referenced anywhere in the book and tells you how to install it on the three rootfs paths.

TL;DR. During learning, use Ubuntu-base (Ch 35A) and apt install .... When you ship, use Buildroot (Ch 35) and flip the corresponding Kconfig flag. BusyBox-only (Ch 31) does not have most of these.

A.1 Three rootfs paths, briefly recapped

Rootfs	Size	Get tools by	Best for
BusyBox hand-built (Ch 31)	~3 MB	hand-cross-compile each tool; mostly not worth it	“Hello, world” + learning the boot pipeline
Buildroot (Ch 35)	30–80 MB	make menuconfig → flip BR2_PACKAGE_* → rebuild	Production shipping
Ubuntu-base (Ch 35A)	~600 MB	apt install <name> on the target	Learning, prototyping, dev kit

The choice is not permanent. Many teams develop a feature on Ubuntu-base, validate, then port the same configuration to Buildroot for the shipping image.

A.2 Why BusyBox-only doesn’t get you very far

BusyBox is one binary with ~240 applets (ls, sh, mount, ip, mdev, …). It covers the GNU coreutils + a slice of net-tools + sysvinit. What it does not contain is anything specialised: no alsa-utils, no bluez, no gstreamer, no chrony, no gdbserver. The applet list is fixed at compile time. Adding bluetoothctl to a BusyBox-only system means cross-compiling BlueZ separately and installing it next to BusyBox — which is what Buildroot does for you with one Kconfig flag.

Reach for BusyBox-only when the goal is to understand what an init does and what a rootfs minimum looks like. Once you want to do something with hardware (audio, BT, WiFi, modem, GPS, …) you need either Buildroot or Ubuntu-base.

A.3 Tool index — every name used in this book

For each tool: what it is, chapters that use it, Ubuntu-base install, Buildroot Kconfig, and a short note.

Networking + iproute2

Tool	Chapters	Ubuntu-base	Buildroot
ip (iproute2)	52, 55C, 91–94, 102, 108, 115	preinstalled	BR2_PACKAGE_IPROUTE2=y
dhclient, dhcpcd	24, 52, 91–93	preinstalled / apt install isc-dhcp-client	BR2_PACKAGE_DHCPCD=y
ifupdown (ifup, ifdown)	various	apt install ifupdown	BR2_PACKAGE_IFUPDOWN=y
NetworkManager (nmcli)	91–94, 102	apt install network-manager	BR2_PACKAGE_NETWORK_MANAGER=y
tcpdump	24, 52, 102, 108, 115	apt install tcpdump	BR2_PACKAGE_TCPDUMP=y
iperf3	52, 55E, 91–94, 115	apt install iperf3	BR2_PACKAGE_IPERF3=y
ethtool	52, 115	apt install ethtool	BR2_PACKAGE_ETHTOOL=y
ss (sockstat)	52, 102, 120	preinstalled	BR2_PACKAGE_IPROUTE2=y (bundled)
nfs-kernel-server (host)	24, 31, 35A	apt install nfs-kernel-server	n/a (host-only)
tftpd-hpa (host)	24, 26	apt install tftpd-hpa	n/a (host-only)

WiFi + wireless

Tool	Chapters	Ubuntu-base	Buildroot
wpa_supplicant	55E, 91–94	apt install wpasupplicant	BR2_PACKAGE_WPA_SUPPLICANT=y
iw	91–94	apt install iw	BR2_PACKAGE_IW=y
hostapd (AP mode)	91	apt install hostapd	BR2_PACKAGE_HOSTAPD=y
wireless-regdb	91	preinstalled	BR2_PACKAGE_WIRELESS_REGDB=y
crda (legacy regdb tool)	91	preinstalled (deprecated, merged into kernel)	typically not needed on modern kernels
WiFi firmware blobs	91–94	apt install firmware-realtek firmware-brcm80211 …	BR2_PACKAGE_RTL_BT_FIRMWARE=y, etc. (one per chip)

Bluetooth

Tool	Chapters	Ubuntu-base	Buildroot
BlueZ stack (bluetoothd)	95–97	apt install bluez	BR2_PACKAGE_BLUEZ5_UTILS=y
bluetoothctl	95–97	bundled with bluez	bundled
btmon, btmgmt, hciattach	95–97	apt install bluez-tools	BR2_PACKAGE_BLUEZ5_UTILS_DEPRECATED=y (legacy hciconfig/hcitool)
bluetooth-meshd + mesh-cfgclient	97	apt install bluez-meshd (Ubuntu 22.04+)	BR2_PACKAGE_BLUEZ5_UTILS=y + experimental mesh support
Pre-built BT firmware	95–97	apt install firmware-misc-nonfree	per-chip firmware package

Cellular (modems)

Tool	Chapters	Ubuntu-base	Buildroot
pppd + chat	24, 55F, 103	apt install ppp	BR2_PACKAGE_PPP=y
ModemManager (mmcli)	55F, 102	apt install modemmanager	BR2_PACKAGE_MODEM_MANAGER=y
libqmi (qmicli)	55F, 102	apt install libqmi-utils	BR2_PACKAGE_LIBQMI=y
libmbim (mbimcli)	55F, 102	apt install libmbim-utils	BR2_PACKAGE_LIBMBIM=y
gpsd + gpspipe, cgps, gpsmon	107	apt install gpsd gpsd-clients	BR2_PACKAGE_GPSD=y
quectel-CM (vendor)	102	not in apt; build from NXP/Quectel repo	not in mainline Buildroot

Audio (ALSA, PulseAudio, GStreamer)

Tool	Chapters	Ubuntu-base	Buildroot
alsa-utils (alsamixer, aplay, arecord)	53, 78, 89, 90	apt install alsa-utils	BR2_PACKAGE_ALSA_UTILS=y
ALSA libraries (libasound2)	53, 89, 90	preinstalled / apt install libasound2-dev	BR2_PACKAGE_ALSA_LIB=y
pulseaudio	optional (Ch 53 sidebar)	apt install pulseaudio	BR2_PACKAGE_PULSEAUDIO=y
pipewire	optional (Ch 53 sidebar)	apt install pipewire	BR2_PACKAGE_PIPEWIRE=y
gstreamer1.0-tools (gst-launch-1.0)	54B, 87, 88	apt install gstreamer1.0-tools	BR2_PACKAGE_GSTREAMER1=y
GStreamer plugins (base/good/bad/ugly)	54B, 87, 88	apt install gstreamer1.0-plugins-{base,good,bad}	BR2_PACKAGE_GST1_PLUGINS_BASE/GOOD/BAD=y
v4l-utils (v4l2-ctl, qv4l2)	54B, 87	apt install v4l-utils	BR2_PACKAGE_V4L_UTILS=y

GPIO / I²C / SPI / sensors / IIO

Tool	Chapters	Ubuntu-base	Buildroot
libgpiod (gpioget, gpioset, gpiomon, gpioinfo)	18B, 44, 78, 99, 111	apt install gpiod	BR2_PACKAGE_LIBGPIOD=y
i2c-tools (i2cdetect, i2cdump, i2cset, i2cget)	18, 46, 64–117 (most cookbook)	apt install i2c-tools	BR2_PACKAGE_I2C_TOOLS=y
spidev-test	47	apt install spi-tools (older) / build manually	BR2_PACKAGE_SPI_TOOLS=y
evtest (input subsystem)	45, 55G, 86, 106	apt install evtest	BR2_PACKAGE_EVTEST=y
libinput-tools	86	apt install libinput-tools	BR2_PACKAGE_LIBINPUT=y
tslib (resistive touch)	86	apt install libts-bin	BR2_PACKAGE_TSLIB=y
IIO sysfs (/sys/bus/iio/devices/)	all sensor chapters	kernel-provided; no userspace install	kernel CONFIG_IIO=y
iio-utils (iio_readdev, iio_info)	various	apt install libiio-utils	BR2_PACKAGE_LIBIIO_TOOLS=y

Storage / filesystem / flash

Tool	Chapters	Ubuntu-base	Buildroot
mtd-utils (flash_erase, nandwrite, flashcp, mtdinfo)	54A, 64	apt install mtd-utils	BR2_PACKAGE_MTD=y
ubi-utils (ubinfo, ubiformat, ubinize)	54A	bundled with mtd-utils	bundled
parted, fdisk, sfdisk	19, 31, 121	preinstalled	BR2_PACKAGE_PARTED=y / BR2_PACKAGE_UTIL_LINUX_FDISK=y
e2fsprogs (mkfs.ext4, e2fsck, tune2fs)	19, 31, 35B	preinstalled	BR2_PACKAGE_E2FSPROGS=y
dosfstools (mkfs.vfat)	121, 125	preinstalled	BR2_PACKAGE_DOSFSTOOLS=y
cryptsetup (LUKS)	124 (sidebar)	apt install cryptsetup	BR2_PACKAGE_CRYPTSETUP=y
veritysetup (dm-verity)	124	bundled with cryptsetup	bundled
overlayfs (kernel feature, not a tool)	35B	n/a	kernel CONFIG_OVERLAY_FS=y

Time + NTP + PPS

Tool	Chapters	Ubuntu-base	Buildroot
chrony (chronyc)	107, 117	apt install chrony	BR2_PACKAGE_CHRONY=y
ntpd (legacy alternative)	117	apt install ntp	BR2_PACKAGE_NTP=y
pps-tools (ppstest)	107	apt install pps-tools	BR2_PACKAGE_PPS_TOOLS=y
hwclock	18C, 117	preinstalled (util-linux)	BR2_PACKAGE_UTIL_LINUX_HWCLOCK=y

CAN / RS-485 / industrial

Tool	Chapters	Ubuntu-base	Buildroot
can-utils (candump, cansend, cangen, canplayer, cansniffer, isotpsend, isotprecv, cangw)	55C, 110	apt install can-utils	BR2_PACKAGE_CAN_UTILS=y
libsocketcan	55C, 110	apt install libsocketcan2 libsocketcan-dev	BR2_PACKAGE_LIBSOCKETCAN=y
libmodbus (modbus_*)	108	apt install libmodbus5 libmodbus-dev	BR2_PACKAGE_LIBMODBUS=y
pymodbus (Python)	108	pip install pymodbus	BR2_PACKAGE_PYTHON3_PYMODBUS=y

Identification / NFC / Fingerprint

Tool	Chapters	Ubuntu-base	Buildroot
libnfc-bin (nfc-list, nfc-mfultralight, …)	105	apt install libnfc-bin libnfc-dev	BR2_PACKAGE_LIBNFC=y
neard (NFC daemon, neardctl)	105	apt install neard	BR2_PACKAGE_NEARD=y
mfoc / mfcuk (Mifare Classic key recovery; security research)	105 sidebar	apt install mfoc mfcuk	not in mainline Buildroot
fprintd + libfprint	106	apt install fprintd libfprint-2-2	BR2_PACKAGE_FPRINTD=y
pamu2fcfg (2FA)	106	apt install libpam-u2f	BR2_PACKAGE_LIBPAM_*

Smart-home / mesh / IoT

Tool	Chapters	Ubuntu-base	Buildroot
mosquitto broker	100, 114, all MQTT examples	apt install mosquitto	BR2_PACKAGE_MOSQUITTO=y
mosquitto-clients (mosquitto_pub, mosquitto_sub)	as above	apt install mosquitto-clients	bundled when mosquitto enabled
zigbee2mqtt	100	Node 18+: apt install nodejs npm; then npm install -g zigbee2mqtt	non-trivial; usually run from a separate container
OpenThread Border Router (otbr-agent)	100	build from openthread/ot-br-posix source	non-trivial; typically self-built
chip-tool (Matter)	100	build from project-chip/connectedhomeip	non-trivial

Debug / tracing / profiling

Tool	Chapters	Ubuntu-base	Buildroot
gdb-multiarch (host)	118, 120, 125A	apt install gdb-multiarch	n/a (host-only)
gdbserver (target)	120, 125A	apt install gdbserver	BR2_PACKAGE_GDB=y + BR2_PACKAGE_GDB_SERVER=y
strace	120	apt install strace	BR2_PACKAGE_STRACE=y
ltrace	120	apt install ltrace	BR2_PACKAGE_LTRACE=y
perf (linux-tools)	120	apt install linux-tools-generic (kernel-version-matched)	BR2_PACKAGE_LINUX_TOOLS_PERF=y
valgrind (memcheck)	120 sidebar	apt install valgrind	BR2_PACKAGE_VALGRIND=y
trace-cmd + kernelshark	119	apt install trace-cmd kernelshark	BR2_PACKAGE_TRACE_CMD=y (kernelshark builds separately on host)
bcc, bpftrace	119	apt install bpfcc-tools bpftrace	BR2_PACKAGE_BCC=y / BR2_PACKAGE_BPFTRACE=y (kernel must have BPF + BTF)
coredumpctl (systemd)	120	bundled with systemd	requires systemd init
OpenOCD (host)	118	apt install openocd	n/a (host-only)

Build infrastructure (host)

Tool	Chapters	Ubuntu-base (host)
Cross toolchains (arm-none-linux-gnueabihf-gcc, arm-none-eabi-gcc)	3, 6, 122	Arm GNU Toolchain tarballs installed under ~/imx6ull/toolchains/
crosstool-NG (build your own toolchain)	122	apt install autoconf bison flex texinfo unzip; clone crosstool-ng
bison, flex, bc, libssl-dev (kernel build)	25, 122	apt install build-essential bison flex bc libssl-dev
device-tree-compiler (dtc)	27, 27A	apt install device-tree-compiler
u-boot-tools (mkimage, mkenvimage)	11, 19, 23	apt install u-boot-tools
qemu-user-static (chroot foreign arch)	35A	apt install qemu-user-static
binfmt-support	35A	apt install binfmt-support
imx_usb_loader, uuu (i.MX SDP flashing)	3, 8, 24, 121A	apt install imx-usb-loader; build uuu from nxp-imx/mfgtools

OTA / images / production

Tool	Chapters	Ubuntu-base	Buildroot
RAUC (rauc)	125	apt install rauc	BR2_PACKAGE_RAUC=y
SWUpdate	125	build from source (sbabic/swupdate)	BR2_PACKAGE_SWUPDATE=y
Mender (mender-client, mender-cli)	125	apt install mender-client; mender-cli separate	BR2_PACKAGE_MENDER=y (community); commercial via Mender
casync (delta-update chunking)	125	apt install casync	BR2_PACKAGE_CASYNC=y
wic (Yocto image creator)	123A	bundled with Yocto / bitbake	n/a

Secure boot / TEE

Tool	Chapters	Ubuntu-base	Buildroot
NXP CST (Code Signing Tool)	124	download from NXP site; non-redistributable	not in Buildroot
openssl (key generation)	124	preinstalled	BR2_PACKAGE_OPENSSL=y
OP-TEE (tee-supplicant)	124	build from OP-TEE/optee_os and OP-TEE/optee_client	BR2_PACKAGE_OPTEE_CLIENT=y
imx_habtool (HAB CSF helper)	124	from NXP CST tarball	not in Buildroot

A.4 Quick-start “install everything” cheat sheets

Ubuntu-base one-liner

For a learning dev kit (any chapter in the book usable after this):

sudo apt update
sudo apt install -y \
    i2c-tools spi-tools gpiod libgpiod-dev \
    alsa-utils libasound2-dev \
    gstreamer1.0-tools gstreamer1.0-plugins-base gstreamer1.0-plugins-good gstreamer1.0-plugins-bad \
    v4l-utils libv4l-dev \
    bluez bluez-tools \
    wpasupplicant iw hostapd wireless-regdb \
    network-manager modemmanager libqmi-utils libmbim-utils \
    ppp \
    gpsd gpsd-clients pps-tools chrony \
    can-utils libsocketcan-dev libmodbus5 libmodbus-dev \
    libnfc-bin libnfc-dev neard \
    fprintd libfprint-2-2 \
    mosquitto mosquitto-clients \
    mtd-utils dosfstools parted cryptsetup \
    iperf3 tcpdump ethtool \
    gdb-multiarch gdbserver strace ltrace valgrind \
    trace-cmd \
    rauc casync \
    device-tree-compiler u-boot-tools

That’s about 400 MB of additional disk on the target. Drop the lines you don’t need.

Buildroot Kconfig fragment

Drop into your configs/myboard_defconfig (or merge via make menuconfig):

BR2_PACKAGE_I2C_TOOLS=y
BR2_PACKAGE_LIBGPIOD=y
BR2_PACKAGE_LIBGPIOD_TOOLS=y
BR2_PACKAGE_ALSA_UTILS=y
BR2_PACKAGE_ALSA_LIB=y
BR2_PACKAGE_GSTREAMER1=y
BR2_PACKAGE_GST1_PLUGINS_BASE=y
BR2_PACKAGE_GST1_PLUGINS_GOOD=y
BR2_PACKAGE_GST1_PLUGINS_BAD=y
BR2_PACKAGE_V4L_UTILS=y
BR2_PACKAGE_BLUEZ5_UTILS=y
BR2_PACKAGE_BLUEZ5_UTILS_DEPRECATED=y
BR2_PACKAGE_WPA_SUPPLICANT=y
BR2_PACKAGE_IW=y
BR2_PACKAGE_HOSTAPD=y
BR2_PACKAGE_NETWORK_MANAGER=y
BR2_PACKAGE_MODEM_MANAGER=y
BR2_PACKAGE_LIBQMI=y
BR2_PACKAGE_LIBMBIM=y
BR2_PACKAGE_PPP=y
BR2_PACKAGE_GPSD=y
BR2_PACKAGE_PPS_TOOLS=y
BR2_PACKAGE_CHRONY=y
BR2_PACKAGE_CAN_UTILS=y
BR2_PACKAGE_LIBSOCKETCAN=y
BR2_PACKAGE_LIBMODBUS=y
BR2_PACKAGE_LIBNFC=y
BR2_PACKAGE_NEARD=y
BR2_PACKAGE_FPRINTD=y
BR2_PACKAGE_MOSQUITTO=y
BR2_PACKAGE_MTD=y
BR2_PACKAGE_DOSFSTOOLS=y
BR2_PACKAGE_E2FSPROGS=y
BR2_PACKAGE_PARTED=y
BR2_PACKAGE_CRYPTSETUP=y
BR2_PACKAGE_IPERF3=y
BR2_PACKAGE_TCPDUMP=y
BR2_PACKAGE_ETHTOOL=y
BR2_PACKAGE_GDB=y
BR2_PACKAGE_GDB_SERVER=y
BR2_PACKAGE_STRACE=y
BR2_PACKAGE_LTRACE=y
BR2_PACKAGE_VALGRIND=y
BR2_PACKAGE_TRACE_CMD=y
BR2_PACKAGE_RAUC=y
BR2_PACKAGE_CASYNC=y
BR2_PACKAGE_OPTEE_CLIENT=y

This will bloat the image by ~40 MB. That’s expected for a dev-image; production images trim to only what they ship.

A.5 Per-Part cheat sheets

If you only want the tools for the Part you’re reading right now:

Part VI — Driver development

# Ubuntu-base on target
apt install i2c-tools gpiod alsa-utils v4l-utils gstreamer1.0-tools \
            bluez wpasupplicant iw modemmanager libqmi-utils \
            mtd-utils can-utils evtest

Part VII — Device cookbook

Same as Part VI, plus:

apt install libnfc-bin neard fprintd \
            libmodbus-dev mosquitto-clients \
            gpsd gpsd-clients pps-tools chrony \
            iperf3 tcpdump

Part VIII — Debug, production, advanced

# On the host
apt install gdb-multiarch openocd build-essential bison flex bc libssl-dev \
            qemu-user-static binfmt-support u-boot-tools device-tree-compiler

# On the target (debug image only — strip for production)
apt install gdbserver strace ltrace valgrind trace-cmd perf \
            rauc casync

Part IX — Applied virtualization

# On the host
apt install qemu-system-arm qemu-system-aarch64 gdb-multiarch \
            device-tree-compiler u-boot-tools bridge-utils

# Hypervisor builds also need the normal kernel/U-Boot build tools above.
# Xen, Jailhouse, Zephyr, and STM32MP1-specific tooling are pinned inside
# their chapters because version drift matters.

A.6 Pitfalls

• libgpiod v1 vs v2. The CLI changed: gpioget --chip=gpiochip0 18 (v2) vs gpioget gpiochip0 18 (v1). Ubuntu 24.04+ ships v2; older Buildroot trees ship v1. Match documentation to your version.

• GStreamer plugin sets. “base” + “good” + “bad” cover ~95 % of pipelines; “ugly” adds patented-codec elements (h264, mp3). Add gstreamer1.0-libav for ffmpeg-backed elements. Ubuntu separates these into named packages; Buildroot uses BR2_PACKAGE_GST1_PLUGINS_*=y.

• WiFi firmware blobs are non-redistributable. Ubuntu ships them in firmware-iwlwifi, firmware-realtek, etc.; Buildroot has corresponding packages but you may need BR2_LEGAL_INFO=y and to accept the licenses.

• bluez 5.x vs bluetooth-meshd. Mesh support is a separate daemon (bluetooth-meshd); installing bluez alone does not give you mesh.

• mosquitto broker + clients. “Clients” without “broker” still works — you just connect to a remote broker. Drop BR2_PACKAGE_MOSQUITTO=y and keep BR2_PACKAGE_MOSQUITTO_CLIENTS=y if you don’t host the broker.

• zigbee2mqtt is Node.js, not a C package. Run from npm, or containerize.

• OpenThread / Matter require building from source. No clean apt or Buildroot package; expect 30–90 min of build time and tracking upstream master.

• NXP CST (Code Signing Tool) is not redistributable. Download from the NXP site after registration; do not check it into a public repo.

• mfoc/mfcuk are offensive-security tools. Many jurisdictions restrict cloning RFID cards. Use for authorized assessment only.

• systemd-only utilities. journalctl, coredumpctl, systemd-analyze only work if your init is systemd. BusyBox-init / runit / sysvinit systems use dmesg, gdb on /var/lib/cores/*, and their own benchmarking instead.

• pip install on production images. Convenient on dev kit; ruins reproducibility on shipping firmware. Use Buildroot’s BR2_PACKAGE_PYTHON3_* packages or vendor your wheels.

A.7 Going deeper

• Buildroot manual, “Package recipes” chapter — the canonical reference; lists every BR2_PACKAGE_* symbol.

• Yocto Project Layer Index (https://layers.openembedded.org/) — search any tool name to find the recipe.

• Debian / Ubuntu packages.ubuntu.com — search to verify the exact package name for any tool.

• apt-file (apt install apt-file && apt-file update) — search “which package ships this binary?”: apt-file search bin/gpioget.

• Per-chapter “Tooling” boxes — most chapters that depend on a specific tool now carry a one-line install hint at the top of the chapter; this appendix is the canonical full reference.