ATI Radeon HD3470 and RadeonHD drivers

[kliput]

Hello everyone!
It's not an issue in openSUSE, but I would like to ask some questions about the radeonhd driver shipped with OS 11.1.
On other distros (for example Slackware, ArchLinux) and also other operating systems (OpenSolaris) radeonhd driver doesn't work with my graphics card. I've tried with various kernels (my notebook works properly from kernel 2.6.29.1, it have repaired an ACPI and MTRR issue) and few Xorg-server versions. It's known issue from X.Org Wiki - radeonhd: "10.7. The driver doesn't start on my laptop. I have 4GB of main memory, BTW" because I've got an ASUS M51Tr notebook with two graphic cards (one: Radeon HD3470 and second: integrated Radeon HD3200) and 3GB of RAM (more than 2GB, which cause problems).
Fortunately, this driver runs successfully on openSUSE 11.1 (also with kernel upgraded to 2.6.30 from factory repo).
Could You tell me, how this can work? Is it repaired by special SUSE kernel patches or Xorg patches? Or some other thing?
Thanks in advance for answers.

PS. Sorry for my poor English
PS2. RadeonHD driver doesn't work perfect, it has some issues, but it's another thread.