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List:       yaffs
Subject:    [Yaffs] Re: Yaffs support in 2.4.20 kernel
From:       Sergei Sharonov <sergei.sharonov () halliburton ! com>
Date:       2005-05-18 14:34:23
Message-ID: loom.20050518T160237-964 () post ! gmane ! org
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Hi,
> 	I m using the jffs2 filesyem support on my linux kernel version 2.4.20 and
MTD subsystem version 2.6.9 with
> BBT and ECC management support in MTD subsytem.Is linux kernel 2.4.20 supports
the yaffs filesystem ?
> Also I have a 16MB of NAND flash on my system which is ARM based.Which
filesystem(JFFS <at>  or YAFFS) is good in
> terms of the utilization of the storage space of the NAND flash.

First, in order to get stable MTD NAND support you will want recent MTD
snapshot, and as you probably know recent MTD does not support 2.4 kernels. I
hear I it can be backported but you are pretty much on your own. I am not sure
what you mean by MTD 2.6.9 - is it pulled out of 2.6.9 kernel? You are better
off using a snapshot from MTD site.
Second - there some major diffrences between jffs2 and yaffs:
1. yaffs has _much_ faster boot time, but with such small (16 MB) NAND you may 
be OK with jffs2. Just don't do small size writes to it. 4 kB is optimal.
2. jffs2 offers compression and yaffs does not. 
3. jffs2 has high RAM consumption - depends on the node size but I heard an
estimate of 4 MB RAM per 128 MB NAND.
4. I believe there is much wider user base for jffs2 - just look at the trafic
volume on the mailing lists.
5. I hear yaffs is robust with respect to power failures, but it does not pass
my power fail test at the moment. I do not claim that it is yaffs issue - it may
be a problem with my port. I asked if other people did any power cycling tests 
but did not get any replies. I have not tested jffs2 in this regard but I 
know somebody who did ~3000 power cycles without any problems.
6. I believe yaffs has seen more use on 2.4 kernels than 2.6.

Sergei Sharonov







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