ubifs version 1 compatibility

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.

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?

Quoted 5 lines · Hamish Moffatt

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.

Quoted 8 lines

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.

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.

Yes our version 1 media is from pre-mainline UBIFS and we took our chances by including it. We are shipping one product using 2.6.24 with old backported UBIFS and it's working very well. I don't have any expectations of support for the old version, so thanks for your assistance thus far.

Fortunately the kernel upgrade is for a newer product where we have some more flexibility in fixing this problem.

We can upgrade our boot loader to 2.6.29 also so that it can read UBIFS v4 media. This has to be co-ordinated with the main firmware image but this is reasonable.

We do have one volatile UBIFS volume that we want to preserve. Is there any way we could convert it? For example a user-space utility that could read the old media version?

Maybe before upgrade we could run mkfs.ubifs using the contents of the existing volume to create the new format, unmount it and ubiupdatevol it..

On Thu, 2009-03-26 at 18:44 +1100, Hamish Moffatt wrote:
makes it very difficult to turn old image into new one. This will basically mean we need:

1. extract files from the old image
2. feed them to mkfs.ubifs.

Quoted 2 lines

Maybe before upgrade we could run mkfs.ubifs using the contents of the existing volume to create the new format, unmount it and ubiupdatevol it..

The easiest way to do this is to boot the old kernel, e.g. in vmware, extract the files using the nandsim technique:
http://www.linux-mtd.infradead.org/faq/ubifs.html#L_ubifs_nandsim

then feed them to mkfs.ubifs.

But yes, a user-space utility to extract files from an image would be of course nicer, but again it is something which is not easy to do.

Quoted 10 lines · Artem Bityutskiy

On Thu, 2009-03-26 at 18:44 +1100, Hamish Moffatt wrote:
makes it very difficult to turn old image into new one. This will basically mean we need:

1. extract files from the old image
2. feed them to mkfs.ubifs.

Quoted 2 lines

Maybe before upgrade we could run mkfs.ubifs using the contents of the existing volume to create the new format, unmount it and ubiupdatevol it..

Quoted 5 lines

The easiest way to do this is to boot the old kernel, e.g. in vmware, extract the files using the nandsim technique:
http://www.linux-mtd.infradead.org/faq/ubifs.html#L_ubifs_nandsim

then feed them to mkfs.ubifs.

Well I have these files on embedded devices out in the real world. The volume is storing user data, so I need to do this change in-place.

Quoted 11 lines · Hamish Moffatt

Quoted 10 lines · Artem Bityutskiy

On Thu, 2009-03-26 at 18:44 +1100, Hamish Moffatt wrote:
makes it very difficult to turn old image into new one. This will basically mean we need:

1. extract files from the old image
2. feed them to mkfs.ubifs.

Quoted 2 lines

Maybe before upgrade we could run mkfs.ubifs using the contents of the existing volume to create the new format, unmount it and ubiupdatevol it..

Quoted 8 lines

Quoted 5 lines

The easiest way to do this is to boot the old kernel, e.g. in vmware, extract the files using the nandsim technique:
http://www.linux-mtd.infradead.org/faq/ubifs.html#L_ubifs_nandsim

then feed them to mkfs.ubifs.

Well I have these files on embedded devices out in the real world. The volume is storing user data, so I need to do this change in-place.

Let me make sure I understand the need.

So you have devises with v1 format in the wild. You want to upgrade those devices. While upgrading, you will re-write some UBI volumes, but after upgrade the user-data volume should contains exactly the same data as before the upgrade, right?

Quoted 21 lines · Artem Bityutskiy

Quoted 19 lines · Hamish Moffatt

Quoted 7 lines · Artem Bityutskiy

On Thu, 2009-03-26 at 18:44 +1100, Hamish Moffatt wrote:
makes it very difficult to turn old image into new one. This will basically mean we need:

1. extract files from the old image
2. feed them to mkfs.ubifs.

Quoted 8 lines

Quoted 2 lines

Maybe before upgrade we could run mkfs.ubifs using the contents of the existing volume to create the new format, unmount it and ubiupdatevol it..

The easiest way to do this is to boot the old kernel, e.g. in vmware, extract the files using the nandsim technique:
http://www.linux-mtd.infradead.org/faq/ubifs.html#L_ubifs_nandsim

then feed them to mkfs.ubifs.

Well I have these files on embedded devices out in the real world. The volume is storing user data, so I need to do this change in-place.

Quoted 6 lines

Let me make sure I understand the need.

So you have devises with v1 format in the wild. You want to upgrade those devices. While upgrading, you will re-write some UBI volumes, but after upgrade the user-data volume should contains exactly the same data as before the upgrade, right?

Yes, that's what I need.