The ironic thing is that Sony had an excellent hypervisor that did a very good job of sandwalling linux off from the rest of the system. Linux running with game os privileges would allow RSX access, ability to get the security SPU to decrypt data, etc...
Rsx access in other os was never totally disproven, no driver and that same problem will allways exist. rsx never had a driver except for game os unless on the small chance that "cell" demo ibm had running with mac osx was on a prototype "ps3" I put ps3 in quotations because I know it was in a mac case but who knows what motherboard was in it. My guess is it was a off the shelf mac with a cell accelleration board.
I even asked ibm for more info in a few e-mails to different departments but always got the customer service number which would be useless knowing who is probably behind the phone.
Your other problem is going to be to partition the drive correctly, ready for it to take Linux, assuming you can get everything else working. If we can't get the original XMB module installed there doesn't seem any easy way to do this, other than reversing the way the PS3 sets up the partitions.
As I understand it, when you install otheros, it erases your current drive, creates a new PS3 cellfs (gameos format) partition, and then a standard EXT3 partition that takes the linux side.
Some analysis of a 3.15 Linux enabled drive on a PC would be valuable. I only have 3.41, where of course the cellfs is non-readable (but can be dumped using DD on a PC using Linux).
On OtherOS enabled PS3s, you basically have to re-create the CellFS partition with one of two fixed sizes: 10GB or <HDD size>-10GB. Would be interesting to see if the mkfs.self that comes with the leaked SDK still offers the option to create two partitions.
But for starters developers don't have to worry about that since Linux will happily run off a attached USB HDD
What do we know about UPDATE.PUP file formats so far? PUP header and payload. Are we already looking at making a 3.41 firmware masquerade as a 3.42 firmware file?
The PUP files are no problem and can be extracted without a problem. The problem are the PKG files within which are encrypted so ... sorry, no cigar.
Also nouveau is supporting Gallium3D - see freedesktop.org/wiki/Software/gallium There also exists CELL driver for Gallium3D that provides accelerated graphics computed by CELL SPUs - see mesa3d.org/cell.html That page however seems a bit outdated...