added comment and append error to message

cmd/minikube/cmd/start_flags.go

@@ -403,14 +403,15 @@ func getCNIConfig(cmd *cobra.Command) string {
 	return chosenCNI
 }
 
+// getExtraOptions gets Kubernetes extra options from flags
 func getExtraOptions() config.ExtraOptionSlice {
 	extraOptionVals := config.ExtraOptionSlice{}
 	val := viper.GetString(extraOptions)
 	if val == "" {
 		return extraOptionVals
 	}
 	if err := extraOptionVals.Set(val); err != nil {
-		klog.Errorf("Invalid %s flag provided, flag will be ignored", extraOptions)
+		klog.Errorf("Invalid %s flag provided, flag will be ignored: %v", extraOptions, err)
 	}
 	return extraOptionVals
 }

site/content/en/docs/commands/start.md

@@ -45,7 +45,7 @@ minikube start [flags]
       --dry-run                           dry-run mode. Validates configuration, but does not mutate system state
       --embed-certs                       if true, will embed the certs in kubeconfig.
       --enable-default-cni                DEPRECATED: Replaced by --cni=bridge
-      --extra-config ExtraOption          A set of key=value pairs that describe configuration that may be passed to different components.
+      --extra-config string               A set of key=value pairs that describe configuration that may be passed to different components.
                                           		The key should be '.' separated, and the first part before the dot is the component to apply the configuration to.
                                           		Valid components are: kubelet, kubeadm, apiserver, controller-manager, etcd, proxy, scheduler
                                           		Valid kubeadm parameters: ignore-preflight-errors, dry-run, kubeconfig, kubeconfig-dir, node-name, cri-socket, experimental-upload-certs, certificate-key, rootfs, skip-phases, pod-network-cidr