JFFS2 SUMMARY nodes aren't working

Joakim Tjernlund joakim.tjernlund at transmode.se
Tue Mar 27 09:16:56 EDT 2007

On Tue, 2007-03-27 at 14:53 +0200, Ferenc Havasi wrote:
> 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.
> Ferenc

Thanks, but it turned out that summary wasn't my problem. It was
excessive scanning of empty erase blocks that took time.

See my later posts and [PATCH] Speed up mount for cfi_cmdset_0001 users


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