How to display the content of FBO onscreen

Hi All,

Currently, I am working on accelerate 2D drawing in DirectFB using OpenGL ES 2.0, on OMAP3430.
Taking performance into account, I choose FBO as the rendering drawable.
After drawing to a framebuffer object, then how to display the content onscreen?
The FrameBuffer Object is off-screen at all times. Is there any relation between FBO and the “visible framebuffer” provided by DirectFB? such as the address of FBO in the mmaped framebuffer memory.

Any suggestion is appreciable.