Enhance eMMC provisioning scripts and documentation: add troubleshooting section for device connection issues, update flash script to prevent concurrent runs, and improve logging. Adjust deployment scripts to verify presence of boot files in mass-storage-gadget.

chromium-setup/emmc-provisioning/scripts/populate-gadget-on-host.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# Populate /opt/usbboot/mass-storage-gadget64 on the Proxmox host (no rpiboot build).
+# Use when rpiboot works but you see "No 'bootcode' files found" — the gadget dir is empty.
+# Usage: ./populate-gadget-on-host.sh [proxmox_host]
+# Example: ./populate-gadget-on-host.sh root@10.130.60.224
+
+set -e
+PROXMOX="${1:-root@10.130.60.224}"
+BUILD_DIR="/tmp/usbboot-gadget-$$"
+cleanup() { rm -rf "$BUILD_DIR"; }
+trap cleanup EXIT
+
+echo "[$(date -Iseconds)] Cloning usbboot to fetch mass-storage-gadget64 ..."
+mkdir -p "$BUILD_DIR"
+git clone --depth=1 https://github.com/raspberrypi/usbboot "$BUILD_DIR/usbboot"
+
+GADGET="$BUILD_DIR/usbboot/mass-storage-gadget64"
+if [[ ! -d "$GADGET" ]]; then
+  echo "Error: mass-storage-gadget64 not found in clone."
+  exit 1
+fi
+# rpiboot needs at least bootfiles.bin or bootcode*.bin
+if [[ ! -f "$GADGET/bootfiles.bin" && ! -f "$GADGET/boot.img" ]]; then
+  echo "Warning: clone has no bootfiles.bin or boot.img. Trying git lfs pull..."
+  (cd "$BUILD_DIR/usbboot" && git lfs pull 2>/dev/null) || true
+fi
+if [[ ! -f "$GADGET/bootfiles.bin" && ! -f "$GADGET/boot.img" ]]; then
+  echo "Error: mass-storage-gadget64 still has no boot files. Install git-lfs and retry, or run build-and-deploy-usbboot-to-host.sh for a full deploy."
+  exit 1
+fi
+
+echo "[$(date -Iseconds)] Syncing mass-storage-gadget64 to $PROXMOX:/opt/usbboot/ ..."
+ssh "$PROXMOX" "mkdir -p /opt/usbboot"
+rsync -a "$GADGET/" "$PROXMOX:/opt/usbboot/mass-storage-gadget64/"
+echo "Done. Verify with: ssh $PROXMOX 'ls -la /opt/usbboot/mass-storage-gadget64/'"