[OpenWrt-Devel] Current state of extroot, how to use it, what about ubi(fs)

Gergely Kiss mail.gery at gmail.com
Tue Dec 16 17:53:32 EST 2014

On 12/16/2014 07:35 PM, Rafał Miłecki wrote:
> Does it really look for entries in /etc/config/fstab? Or does it
> hardcode to use "rootfs" / "rootfs_data" partitions? Could you explain
> what's the point of all these
> find_block_mtd("rootfs", fs, sizeof(fs));
> find_block_ubi_RO(libubi, "rootfs", fs, sizeof(fs));
> find_block_mtd("rootfs_data", fs_data, sizeof(fs_data));
> find_block_ubi(libubi, "rootfs_data", fs_data, sizeof(fs_data));
> in the main_extroot?

To be the honest, I'm not very familiar with the sources, I only made some slight enhancements
to a patch created by a forum member, see https://forum.openwrt.org/viewtopic.php?pid=257518#p257518

Maybe the developer who wrote the code originally could answer that.

I suspect those functions are there so in case extroot fails, the code can revert
to the flash partition to avoid having an unbootable system.

Not sure of you read already but the bottom of this article might help understanding the logic:


> Also, in my case there is "rootfs_data" MTD partition. I could create
> UBI volume "rootfs_data" on NAND flash, but "block extroot" will still
> pick the MTD partition.

Well, that's how it works now but you can always create a patch if you want to change that behaviour.

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