Re: ubifs version 1 compatibility

[Artem Bityutskiy <dedekind@infradead.org>]

On Thu, 2009-03-26 at 16:15 +1100, Hamish Moffatt wrote:
> Hi Artem and all,
> 
> I'm upgrading my embedded system which uses UBIFS from 2.6.24 (with a
> slightly updated ubifs) to 2.6.29.
> 
> I notice that the new kernel won't read my existing file systems as it
> says they are too old - version 1. The code checks for version 3 or 4 I
> see.
> 
> My application firmware is generated with mkfs.ubifs and programmed via
> ubiupdatevol, but the boot loader on my devices is based on the older
> kernel and won't be able to read it. And I have read-write file systems
> that will be formatted with the old version too.
> 
> 
> Is there any solution?

I've took a brief look. UBIFS went into mainline with format version 4,
and versions 1,2,3 were more development versions. There were changes in
the truncation node format and in inode node format. I would probably
be possible to have compatibility mode, but it is big job :-(

Your boot-loader is Linux kernel-based, right? Does it have write
support, or it is read-only?

Is it possible to upgrade the boot-loader at the same time you upgrade
the kernel on your devices?

Side note: now when u-boot supports UBIFS, we need to re-think our
versioning scheme and strictly preserve R/O compatibility.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)