Hi folks,
i think I'm very near to the solution but i miss something.
Now, after
 
sudo mount -t yaffs2 /dev/mtdblock0 /mnt/mtd

i can create directory and file in /mnt/mtd without any problem and if i type

strings /mtd/dev0

i can see ALL strings that are in my image. I can recognize a lot of string
regarding the application installed in my phone and some similar.

So i think that now the problem can be just two:
sudo mount -t yaffs2 /dev/mtdblock0 /mnt/mtd
1) Different version of yaffs on my phone and on my laptop, so there are some
problem to recognize the oob tags.
2) Different version from mtdutils on my phone and on my laptop.

For the first problem i would to ask you how can i see what is the version of
yaffs file system that is currently running on my phone and if i can find the
same on internet or if i can pull out the module from the phone to computer and
load with insmod. If it work we have the solution with every phone, because we
can pull out the module and load it on laptop in automatic manner.

For the second problem, i pushed a compiled version of "nanddump" for arm on the
phone to make the dump of the data partition, but when i come back on my laptop
i have an other version of mtdutils installed because i can't use the version
precompiled for arm processor. How can i use the same version of mtdutils on
phone and on laptop?

Thanks a lot
Luca
regards