Considering the open wall and thwe wooden wall in the picture are now replaced with a hollow block wall and drywall hanging on it, how could I possible hang a soffit on the drywall, without using the ceiling for support (quiet chaotic ceiling...)?
I need a soffit for a) lights and b) to route the cables for electric and speaker etc.

http://i145.photobucket.com/albums/r212/softtouch_ph/ceiling.jpg

Just imagine, I have a hollow block wall, and screwed to it drywall.
Would it work to screw a 1/2 x 4 through the drywall to the hollow block, and screw the L-Shape part of the soffit to it with brackets?

Care to rephrase your question? I see one block wall with windows and one wooden ceiling (or roof underlayment) supported on box beams of some sort. Is this an open patio or carport by chance?

It was an open room, leading to the backyard. The wooden wall is removed, and the both open sides are closed with hollow blocks, and drywall on top of it.
Some people suggested I should not close the ceiling, because it looks nice, so I took that advice. But now I run into the issue of hanging a small (really just 4.5" wide) soffit on the drywall. Because of the shape of the ceiling, I can not fix the soffit to it, so the drywall (and the hollow blocks) will have to carry the weight of the soffit, which is only for cables and some lights.
My damn camera is broken, so I can not take an actual picture... but I will add a drawing later on.