build-rootfs.sh

#!/usr/bin/env bash
# build-rootfs.sh — reproducible Debian riscv64 rootfs for the LILYGO T-Display-K230
#
# Produces a Debian trixie riscv64 root filesystem with the meshtasticd build/runtime
# dependencies preinstalled, then installs the kernel + DTB + extlinux config from the
# Phase 1 boot build. Meant to run on a Linux host (or WSL Debian) with qemu-user-static
# for the foreign-arch second stage. NOT run on the Windows host directly.
#
# This is the "install your own distro on partition 5" step that k230-debian leaves to
# the user (its own rootfs target is only a stub kernel carrier).
#
# Usage:
#   sudo ./build-rootfs.sh --out ./out/rootfs --suite trixie \
#        --kernel /path/to/ulinux.bin --dtb /path/to/t-display-k230.dtb
#
set -euo pipefail

SUITE=trixie
MIRROR=http://deb.debian.org/debian
ARCH=riscv64
OUT=./out/rootfs
KERNEL=""       # mkimage-wrapped kernel payload (ulinux.bin) from Phase 1
DTB=""          # board DTB from Phase 1
HOSTNAME=k230
ROOT_PW=meshtastic

while [ $# -gt 0 ]; do
  case "$1" in
    --out) OUT="$2"; shift 2 ;;
    --suite) SUITE="$2"; shift 2 ;;
    --mirror) MIRROR="$2"; shift 2 ;;
    --kernel) KERNEL="$2"; shift 2 ;;
    --dtb) DTB="$2"; shift 2 ;;
    --hostname) HOSTNAME="$2"; shift 2 ;;
    *) echo "unknown arg: $1" >&2; exit 2 ;;
  esac
done

command -v debootstrap >/dev/null || { echo "install debootstrap"; exit 1; }
command -v qemu-riscv64-static >/dev/null || echo "warn: qemu-riscv64-static not found (needed for foreign second stage)"

# Build/runtime deps for meshtasticd (from firmware Dockerfile + native portduino.ini).
# libgpiod2.x is what platform-native's LinuxGPIOPin targets; trixie ships libgpiod3.
PKGS="ca-certificates locales sudo openssh-server \
  libgpiod-dev libgpiod3 libyaml-cpp-dev libjsoncpp-dev \
  libbluetooth-dev libusb-1.0-0-dev libi2c-dev libuv1-dev \
  libxkbcommon-dev libinput-dev libsqlite3-dev \
  libx11-dev libsdl2-dev \
  i2c-tools gpiod spi-tools \
  wpasupplicant iw ethtool"

mkdir -p "$OUT"

echo "== Stage 1: debootstrap $SUITE/$ARCH =="
# --foreign so the second stage runs under qemu on a non-riscv64 host.
debootstrap --arch="$ARCH" --foreign \
  --include="$(echo "$PKGS" | tr -s ' ' ',')" \
  "$SUITE" "$OUT" "$MIRROR"

echo "== Stage 2: second stage (qemu) =="
if [ -x /usr/bin/qemu-riscv64-static ]; then
  install -m0755 /usr/bin/qemu-riscv64-static "$OUT/usr/bin/"
fi
chroot "$OUT" /debootstrap/debootstrap --second-stage

echo "== Basic system config =="
echo "$HOSTNAME" > "$OUT/etc/hostname"
chroot "$OUT" bash -c "echo 'root:$ROOT_PW' | chpasswd"
# serial console (matches k230-debian extlinux cmdline: ttyS0,115200)
chroot "$OUT" systemctl enable serial-getty@ttyS0.service || true
# rootfs grows to fill partition on first boot
cat > "$OUT/etc/fstab" <<EOF
/dev/mmcblk1p5  /       ext4  rw,relatime  0 1
EOF

echo "== Install kernel + DTB (Phase 1 artefacts) =="
if [ -n "$KERNEL" ]; then
  install -Dm0644 "$KERNEL" "$OUT/boot/vmlinuz-k230"
fi
if [ -n "$DTB" ]; then
  install -Dm0644 "$DTB" "$OUT/boot/dtbs/t-display-k230.dtb"
fi
# extlinux entry (U-Boot distro boot). Mirrors k230-debian/src/extlinux.conf.
install -d "$OUT/boot/extlinux"
cat > "$OUT/boot/extlinux/extlinux.conf" <<EOF
TIMEOUT 30
DEFAULT l0
MENU TITLE T-Display-K230 boot
LABEL l0
    MENU LABEL Debian (T-Display-K230)
    LINUX /boot/vmlinuz-k230
    FDT /boot/dtbs/t-display-k230.dtb
    APPEND root=/dev/mmcblk1p5 rw rootwait rootfstype=ext4 console=ttyS0,115200n8 earlycon=sbi
EOF

echo "== meshtasticd config =="
install -Dm0644 "$(dirname "$0")/config.yaml" "$OUT/etc/meshtasticd/config.yaml" || \
  echo "note: drop k230-linux/config.yaml into /etc/meshtasticd/ after building meshtasticd"

echo "Done. rootfs at: $OUT"
echo "Next: write this rootfs to SD partition 5 (see k230-debian sdcard.dump layout),"
echo "then flash the Phase 1 SPL/U-Boot to the earlier partitions."