Hi , I am writing Kdrive DDX driver for my graphics card . I am completely new to xorg programming . In my graphics controller i need to specify the source and destination buffer addresses to do the acceleration. According to my understanding (correct me if i am wrong) , application can create windows and pixmaps (drawables) .Xserver will allocate the buffers for the applications.To perform graphics operations on these drawable , application has to pass addresses of drawables to the DDX drivers drawing primitives.And then DDX driver will write those addresses to the hardware registers. I have gone through some DDX drivers from X source code , 1) but i am not getting where exactly the DDX driver writes source and destination addresses to the hardware ??? 2) If i perform graphics operations on pixmap , which APIs copies it to frame buffer ??? 3) In case of windows , does all the windows are drawn on framebuffer directly ???? or windows are drawn offscreen first and then copied to framebuffer. 4) And in case of my graphics controller as i explained earlier , is it possible to use only one pixmap and one window surface to do all the drawings and then copy that data to framebuffer ???? because i can specify two source buffers in my graphics card . So can i use one source buffer as Pixmap and one as Window buffer for graphics operations as source  buffers for  Xserver ??? -Thanks