The quest for 3D graphics access via homebrew/Linux (Other OS) on the PS3 is beginning to progress significantly. Recently, IronPeter managed to blit the push buffer from user land using fifo control registers.
To quote: I was able to run blit push buffer from the user land using fifo control regs. There was some kind of protection. Very weak protection.
It works unstable for now, but it does work. Probably, it's possible to write some kind of 2D support (stretched blits, color fills, etc).
The main question is about 3D support. We need so-called "context objects" to be properly initalized. Probably, hypervisor does this work for us. All we need are handles (and lpar_dma_reports contains something that looks like this handles). To initialize these objects "by hands" we need to access to very special RSX registers, so called RAMIN area.
PS. I investigate RSX with only open-source information. I have no signed NDA with Sony or NVidia.
Not sure how much this differs in relation to what did StrontiumDog did back in June of this year with the PS3 RSX Data Dumps! he shared as libPSGL_dumps_v2-[www.PS3News.com].rar [11.7 MB (12,358,812 bytes].. time will tell I guess.