jffs2 on DOC ?

jffs2 on DOC ?

[Poul Lund Jørgensen]

Hi,

I am looking for a power fail safe way to run a DOC2000 device.

The system I am developing does only do little amount of disk writing so I
have been considering to using two partitions:
a read only boot partition containing the entire linux root and boot dir and
one writeable for the dynamic application files.

But from the mail archive I can see that the two partition solution does not
solve the problem if NFTL is involved as the wear levelling
will be done across partition boundaries, so the writeable partition may
corrupt the readonly.

Another solution would be to run jffs2 on the DOC. But the drivers that
comes with the kernel I use (2.4.18) does not support this.

Are there any version of the mtd drivers that currently support this ?

If no, do there exist a patch that makes the DOC driver compatible with
jffs2 or can anybody supply me with
description of the necessary modifications.

Any advice are appreciated.

Thanks,

Poul Lund Jørgensen

RE: jffs2 on DOC ?

[Pieter Grimmerink]

> -----Original Message-----
> From: linux-mtd-admin@lists.infradead.org
> [mailto:linux-mtd-admin@lists.infradead.org]On Behalf Of Poul Lund
> Jørgensen
> Sent: dinsdag 21 mei 2002 16:49
> To: linux-mtd@lists.infradead.org
> Subject: jffs2 on DOC ?

> Another solution would be to run jffs2 on the DOC. But the drivers that
> comes with the kernel I use (2.4.18) does not support this.

According to David Woodhouse, all that's left to do to make DOC support
JFFS2, is to make the write/read functions handle more than 512 bytes
of data.

I've quickly looked into this, but I'm not sure whether just adding a loop
within these functions would do, as I haven't found how bad sectors
are handled within the write/read functions yet.

I could imagine that the file offset always points to the actual location
in the DOC, so that we could have a write of lets say 4 bytes, and
a bad sector in the middle would then cause the file offset to be increased
with 516, but I'm not sure.

I'll eventually need JFFS2 on DOC, but it isn't currenly the first point on
my list,
so I'm secretly hoping someone will fix it before I need it ;-)

Regards,

Pieter