JFFS2 compression type 7

[Scott Douglass]

I was loading different kernels, and just switched from 2.6.27+ to  
2.6.29+ (rawhide with OLPC patches).

While running my custom 2.6.29-0.256.rc8.git2 kernel, I "init 6" and  
start over. Now none of the kernels I've got installed can boot the XO  
from NAND. All of them (2.6.25 OLPC, 2.6.27 OLPC and mine) give  
various flavors of JFFS2 compression type 7 not supported.

How the heck did I change the compression type on my NAND's JFFS2?

Since no kernels are able to boot my XO now, I'll have to reblast the  
NAND. I'm just curious how this could have happened. I've been  
experimenting with enabling CONFIG_* options such that I can boot my  
custom kernels, and I had got a combination that worked!

I did enable multiple types of compression for JFFS2 however,  
including LZO. Could the type of compression be changed on an already  
created JFFS2 system, at run time by the kernel modules?