Enhance network boot setup script and documentation: automate fetching of Raspberry Pi 4 boot files from GitHub, update TFTP root handling, and improve user instructions for setup. Remove manual steps for file retrieval and clarify echo messages in the setup script.

chromium-setup/emmc-provisioning/scripts/populate-tftpboot-from-git.sh

@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+# Populate /srv/tftpboot with Raspberry Pi 4 / CM4 boot files from the official firmware repo.
+# Run inside the LXC (as root), or from your machine: ./populate-tftpboot-from-git.sh root@10.130.60.141
+# Requires: curl or wget, tar; the LXC must have internet (eth0).
+
+set -e
+TARGET="${1:-}"
+FIRMWARE_URL="https://github.com/raspberrypi/firmware/archive/refs/heads/master.tar.gz"
+TFTP_ROOT="${TFTP_ROOT:-/srv/tftpboot}"
+
+do_populate() {
+  echo "Populating $TFTP_ROOT from Raspberry Pi firmware (GitHub) ..."
+  mkdir -p "$TFTP_ROOT"
+  if [[ -f "$TFTP_ROOT/start4cd.elf" ]]; then
+    echo "start4cd.elf already present; skipping download (remove it to re-fetch)."
+    return 0
+  fi
+  if ! command -v curl >/dev/null 2>&1 && ! command -v wget >/dev/null 2>&1; then
+    echo "Installing curl ..."
+    apt-get update -qq && DEBIAN_FRONTEND=noninteractive apt-get install -y -qq curl
+  fi
+  local tmpdir
+  tmpdir=$(mktemp -d)
+  trap "rm -rf $tmpdir" EXIT
+  if command -v curl >/dev/null 2>&1; then
+    curl -sL "$FIRMWARE_URL" -o "$tmpdir/firmware.tar.gz"
+  else
+    wget -q -O "$tmpdir/firmware.tar.gz" "$FIRMWARE_URL"
+  fi
+  tar xzf "$tmpdir/firmware.tar.gz" -C "$tmpdir"
+  if [[ ! -d "$tmpdir/firmware-master/boot" ]]; then
+    echo "Error: boot folder not found in archive"
+    exit 1
+  fi
+  cp -a "$tmpdir/firmware-master/boot/." "$TFTP_ROOT/"
+  echo "Copied boot files to $TFTP_ROOT ($(ls "$TFTP_ROOT" | wc -l) items)."
+  ls -la "$TFTP_ROOT"/start4*.elf "$TFTP_ROOT"/fixup4*.dat "$TFTP_ROOT"/config.txt 2>/dev/null || true
+}
+
+if [[ -n "$TARGET" ]]; then
+  SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+  scp "$SCRIPT_DIR/populate-tftpboot-from-git.sh" "$TARGET:/tmp/populate-tftpboot.sh"
+  ssh "$TARGET" "bash /tmp/populate-tftpboot.sh"
+  exit 0
+fi
+
+do_populate