Add fabric manager boot and support diagnostics

iso/overlay/usr/local/bin/bee-nvidia-load

@@ -258,6 +258,22 @@ else
     log "WARN: nvidia-smi not found — cannot enable persistence mode"
 fi
 
+# Start or refresh Fabric Manager after the NVIDIA stack is ready. On NVSwitch
+# systems CUDA/DCGM can report "system not yet initialized" until fabric
+# training completes under nvidia-fabricmanager.
+if command -v systemctl >/dev/null 2>&1 && systemctl list-unit-files --no-legend 2>/dev/null | grep -q '^nvidia-fabricmanager\.service'; then
+    if systemctl restart nvidia-fabricmanager.service >/dev/null 2>&1; then
+        log "nvidia-fabricmanager restarted"
+    elif systemctl start nvidia-fabricmanager.service >/dev/null 2>&1; then
+        log "nvidia-fabricmanager started"
+    else
+        log "WARN: failed to start nvidia-fabricmanager.service"
+        systemctl status nvidia-fabricmanager.service --no-pager 2>&1 | sed 's/^/  fabricmanager: /' || true
+    fi
+else
+    log "WARN: nvidia-fabricmanager.service not installed"
+fi
+
 # Start DCGM host engine so dcgmi can discover GPUs.
 # nv-hostengine must run after the NVIDIA modules and device nodes are ready.
 # If it started too early (for example via systemd before bee-nvidia-load), it can