[OpenWrt-Devel] Some standard partition name for extra user data?

Hauke Mehrtens hauke at hauke-m.de
Sun Dec 7 10:05:49 EST 2014

On 12/07/2014 01:30 AM, Rafał Miłecki wrote:
> I've bcm53xx device which has two usable flashes:
> 1) SPI serial flash for CFE + firmware + NVRAM
> 2) NAND flash for extra data
> Because of general design of OpenWrt firmware my image contains two
> partitions: kernel and rootfs (SquashFS). Automatically rootfs_data
> (JFFS2) is created right after rootfs.
> I wanted to make space on NAND flash also usable for OpenWrt. Do you
> have any advice on that?
> 1) The coolest idea would be to use some LVM solution, but I don't
> think we have anything like this ready in OpenWrt. Or do we? AFAIK UBI
> itself can't work as LVM (can't use blocks from several MTD
> partitions)?
> 2) So I was thinking about simply registering that NAND partition with
> some name we could make common across OpenWrt targets. Something like
> "extra_data" or whatever you prefer. User would need to mount it and
> use a proper directory for storing his data. Is there anything like
> this in any other target?
> Yet another solution could be to ignore this few MiB space on serial
> flash and simply use NAND for rootfs_data. But this would:
> 1) Waste some minor space on SPI serial flash
> 2) Would require hacking partitioner to don't create rootfs_data
> 3) Hacking UBI a bit I guess

I assume these device are loading the kernel from serial flash by default.

Have you looked at extroot:
This is used to place the root file system on an external storage.

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