Well, after a lot of failure, suddenly SDL started filling the screen with SDL logos, really fast. It seems that you have to do a ctrl-c while it is waiting to set the video mode, and ignore the returned error code, and killall Xorg, then at framework restart about 85% suddenly the SDL app starts doing video updates by calling "eips ''" after each page flip.
It looks like SDL needs to be modified to not mess with framebuffer locking. When Xorg has it, SDL video setting freezes. When SDL holds uses lock, parrts of the framework (menu and status bar) never draw, even when switching to other screens (press power button off and on draws the menu).
So, the reason everybody has had problems with SDL on the kindles is probably lock contention. Because you can draw to the framebuffer without locking it, SDL just needs to have locking disabled.