JFFS2 SUMMARY nodes aren't working

Ferenc Havasi havasi at inf.u-szeged.hu
Tue Mar 27 08:53:07 EDT 2007

Joakim Tjernlund írta:
> On a fresh JFFS2 root FS image with summary nodes there is no
> difference in mount time when enabling summary support in kernel(2.6.20,
> powerpc).
If you use NOR flash with relatively small erase block, summary will not 
really chance to speed up the mount process.

Anyway you should check the summary is really working or not. Use the 
following way:

Enable the JFFS33 debugging options (min. debug level 1) in your kernel 
configuration and recompile the kernel. You  see the following messages 
in your kernel log. When you load the jffs2 kernel module you can see 
the following message:
"JFFS2 version 2.2. NAND SUMMARY" (in case of summary is enabled, maybe 
the NAND is skipped if you doesn't have writebuffer compiled in).

If summary is enabled and something went wrong, maybe the image on flash 
has no summary info:
"no summary found in jeb 0x%08x. Apply original scan." where %08x is 
replaced by the offset of the jeb.

If you see debug information which begin with "jffs2_sum_" and there is 
no error in your log it means the summary works.


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