Re: zlib compression is failing

[syed khader <sk.syed@yahoo.com>]

Hi 
  I have uClinux2.4.24(which corresponds to 2.4
kernel). It originally had jffs2.1. Since 2.1 was
quite slow, we moved it to jffs2.2 by applying patch
from mtd cvs as follows:

   cvs -d :pserver:anoncvs@cvs.infradead.org:/home/cvs
login (password: anoncvs)
   cvs -d :pserver:anoncvs@cvs.infradead.org:/home/cvs
co mtd
   cd <mtd-path>/patches
  sh patchin.sh -c -j <kernel-path> 

  The CVS tag was D2004.05.11.18.30.00

  After applying the patch I am seeing the CRC errors.
As per the logs there were zlib error messages which I
thought were the reason behind CRC errors.

Regarding this link you dont need to register: you can
select free service and download the file directly

http://rapidshare.de/files/20655260/jffs2crclog.txt.html



--- J�rn Engel <joern@wohnheim.fh-wedel.de> wrote:

> Side note: You might want to read the list
> etiquette.  Open source
> taste is a bit different and usually frowns upon
> things that are
> perfectly acceptable in companies.  In particular,
> when writing mails
> you should only quote relevant bits from the last
> mail, remove
> everything else, and write your answers underneith
> the quoted text you
> are referring to.  And here is the full thing:
> http://www.infradead.org/~dwmw2/email.html
> 
> On Tue, 16 May 2006 23:25:52 -0700, syed khader
> wrote:
> > 
> >   in the logs I am seeing the following error
> > messages:
> > 
> > zlib compressed 68 bytes into 77; failing
> > 
> >   why does zlib compression fail?
> 
> When compressing data, there is always the chance
> that data is
> actually being _expanded_ instead of compressed. 
> Imaging compressing
> a compressed file.  Zlib has to add a small header
> and then tries to
> compress the data, which doesn't work.  So it simply
> stores the data
> verbatim after the header, resulting in bigger data
> than before.
> 
> When this happens, jffs2 doesn't want to store the
> bigger "compressed"
> data, but just the plain uncompressed data, saving a
> little flash
> space.
> 
> Quite interesting, though, are the sizes.  68 bytes
> is exactly a jffs2
> inode header.  It makes me a bit uneasy if that
> cannot be compressed.
> So maybe it is time to finally ask some basic
> questions:
> o What kernel version are you using?
> o Are there any patches on top of it?
> o Is the mtd/jffs2 code from above kernel version or
> from cvs/git?
> 
> > > Here is the link to the log:
> > >
> >
>
http://rapidshare.de/files/20655260/jffs2crclog.txt.html
> 
> I just see a page telling me to subscribe to some
> service.  Don't you
> have some other webspace you could use?
> 
> J�rn
> 
> -- 
> I've never met a human being who would want to read
> 17,000 pages of
> documentation, and if there was, I'd kill him to get
> him out of the
> gene pool.
> -- Joseph Costello
> 
>
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