Dumb question coming from someone who is more of an admin than a developer.  Although I did build and run a dev lab at 
Sun in the early days of Solaris Nevada.

What kernel source version or branch will your current git tree patch to and compile with?

I have tried everything from 3.5rc1 to Linus's current git tree.  It breaks DRBD.  Once I disable DRBD in the config it 
fails at target_core_iblock.c.  So I never get a full build.

So either I am doing something obviously wrong or ???

I'd love to test this out and help with debugging.  I have plenty of hardware and interest in it working well.  I can 
even provide you access to debug when I hit an issue.

What error output can I provide and can you point me to good trees?

I appreciate it and I am glad to see that someone is finally making the effort to get a real, working block cache object 
into the kernel.  I will help in any way I can.

Jason