I'm not sure there is a standard here. There are some people I play with where I wouldn't even dream this is a penalty double, and there are some where I would suspect it is. Anyway, I bid 2♠. Passing is too risky for me if I don't even know what partner's x is. If I knew it was penalty, I would pass, since I have two trumps I didn't promise. I don't have great experiences passing out penalty doubles like this, though, so I could be easily convinced that 2♠ is better anyway.