[U-Boot-Users] U-boot 1.2.0 JFFS2, and NAND flash

[Joakim Tjernlund]

On Mon, 2007-10-15 at 12:32 +0200, Detlev Zundel wrote:
> Hi Matt,
> 
> > I'm got an AT91RM9200 and an 16 MB ST Micro NAND flash, partitioned into
> > 3 blocks of 8, 4 and 4 MB.  U-boot boots linux from the first 8MB
> > partition, and doesn't go searching in the others unless it's necessary.
> >
> > The JFFS2 scan for this takes 1:45.  I believe I followed all the
> > instructions in the docs for setting up the NAND flash, and other than
> > seeming to be really slow, it seems to operate just fine.  
> >
> > When I use nand write.jffs2 to write the image, it doesn't take nearly
> > this long.
> >
> > Has anyone else had a similar experience?  Is there some configuration
> > or other tip someone might be able to give me as to why this is so slow?
> 
> As mentioned several times on this mailing list, this is a "feature"
> of the data structures used by JFFS2.  So as not to repeat myself too
> much, JFFS2 has to find the "current" data blocks for the files urging
> it to scan the whole partition.

This is not entierly true. The scaning can be made much faster.
There was/is a patch on the ML that improves the scaning speed
significantly. Search for subject "jffs2 fsload - SOLVED"
Not sure if that patch impl. reduced scanning of empty EBs, scanning
all empty space is very time consuming.

 Jocke

> 
> A simple workaround - also mentioned a few times already - is to use a
> small partition for what is needed during booting.
> 
> Cheers
>   Detlev
>