Yes, I got a successful build.
First tests: very unstable.
Loading a picture.
Changing precision to 16 Bit
changing colors (by "Values") -> crash
Painting works but is very slow.
still lots of testing. More maybe tomorrow...

almost...
As I said, there are some functions missing in Babl 0.1.11
There were changes in Babl on, I think 5th may. If you got your Babl later - voila.
If not (as I expect), you have to get Babl source with the latest patches, then compile it.
It will go, believe me, I did it and it worked (Have a look at the babl git repository)
The version didn't change, it is still 0.1.11, so this can be confusing.
Missing functions, hmm, I would call it 0.1.12...

Yeah, it works now! Thanks guys!

I tried the 16-bit mode with some gradients, it looks real nice but it's a bit buggy... some stray pixels show up that shouldn't be there.

That's what I used w/o any such messages.
From your error log I see that you d/led to your home directory.
Why not to /root ?
And do the compiling as root too,don't use sudo.
Don't worry about getting hacked,this is Linux.
Gerard.

Because I like to keep stuff in my home.
This is Linux, you can use it the way that feels best for you...


On another note, I tried to uncheck "use gegl" just to see what happens, and it crashed gimp... guess they really have ported it to use gegl only then

Just noticed that samj has 2.9.1 compiled in a Virtual Box package. Might be of interest to you.

"Here is a new version of VirtualBox running GimpEVAL. Cette version est faite avec la distribution Ubuntu "Xubuntu 12.04 LTS (Precise Pangolin)". This version is made with the Ubuntu distribution "Xubuntu 4.12 LTS (Precise Pangolin)."

http://samjcreations.blogspot.com/

I am downloading Sams Gimp-2.8 32 bit portable now. Thanks!

I d/led gimp-2.9.1 again together with babl-0.1.11 and gegl-0.2.0.
I enabled 16bit float and I have no color management.
But paint brush lags behind,selections work normal.
I wish the devs would give this priority otherwise nobody will upgrade I think.
Gerard.

I'm testing GIMP 2.9 from 05/05/2012 (Ubuntu 12.04 64 bit).
The version is very unstable (for me no rules when it suddenly turns off) - but I'm glad that there is a chance for very rapid development "Goat Invasion"
I think maybe in a few months everything will be OK.
So far - the effort to install - just for curiosity ...