Seem to have found alot of questions with regards to the radeonfb framebuffer splash but not too many solutions so I've been doing some playing around with it. Haven't worked it all out yet, but hopefully this might help some of you.
Two kernel options to consider:
1) Vesafb-tng
2) Radeonfb
1) Vesafb-tng works fine and manages the gensplash framebuffer without a problem. Just follow the Wiki guide [url=
http://gentoo-wiki.com/HOWTO_fbsplash]here[/url. It had me set up and going no problem. Be sure to use vesafb and not vesafb-tng in your grub file though! This fooled me for a while. e.g.
video=vesafb:ywrap,pmipal,1400x1050-24@85 splash=verbose,theme:emergence
To get it showing up on all screens (alt-f#)
rc-update add splash default
2) Just out of perversity I tried the radeonfb as well. Deleted the vesafb option from the kernel and tried the radeonfb on its own. Make sure you include the DDC/I2C for ATI support as well. I also added the debugging option (directly beneath). Interestingly enough, it aborted and dropped back to the default tux gensplash at 640x480. So it was obviously missing all the arguments passed to it, including the splash theme. This is where I checked the debugging option in the kernel and dmesg notified me that it was grabbing parameters from the bios. I edited the grub line so that it looked like
video=radeonfb splash=verbose,theme:emergence
and it worked fine - dropped into a 1400x1050 display (default for my lcd I guess). Now - were these the parameters picked up from bios? Passing it vga options doesn't work as well, so it doesn't behave like vesafb (as opposed to vesafb-tng). It could be that the radeonfb driver will only work at a single default setting, or perhaps I've just got my frequencies and resolutions set incorrectly? Not sure. Perhaps someone more knowledgeable can say, but at least it provides some info to those out there trying with it.
Cheers,
Daniel.