Попробуй это.Работает
menu.xml
<item
android:id="@+id/action_search"
android:icon="@android:drawable/ic_menu_search"
android:iconifiedByDefault="false"
android:title="Search"
app:actionViewClass="android.support.v7.widget.SearchView"
app:showAsAction="always" />
Java-код:
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.sol_menu, menu);
MenuItem menuItem = menu.findItem(R.id.action_search);
SearchView searchView = (SearchView) menuItem.getActionView();
searchView.setIconified(false);
super.onCreateOptionsMenu(menu);
}