WP 8.1 Portrait mode

I found out that changing resolution after game start is the solution in some sort. Just like this:

graphics.PreferredBackBufferWidth = 1080;
graphics.PreferredBackBufferHeight = 1920;
graphics.ApplyChanges();

or

graphics.PreferredBackBufferWidth = graphics.GraphicsDevice.Viewport.Height;
graphics.PreferredBackBufferHeight = graphics.GraphicsDevice.Viewport.Width;
graphics.ApplyChanges();

or if you want to do it in game1()

int tmp = graphics.PreferredBackBufferWidth;
graphics.PreferredBackBufferWidth = graphics.PreferredBackBufferHeight;
graphics.PreferredBackBufferHeight = tmp;
graphics.ApplyChanges(); 

still I think there is better solution.