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

[Gergely Kiss]

Sorry, I haven't read that post earlier.

So, is this simply about mounting an additional UBIFS partition at boot time?

If so, I believe the best solution would be to extend the
functionality of fstab with a simple (shell) script, as suggested in
the fstab wiki:

"BTRFS, JFS, *UBI* [...] are not supported in /etc/config/fstab. Use
manual scripting."

Would that be possible?


Regards,
Gergely

On 16 December 2014 at 14:39, Flávio Silveira <fggs at terra.com.br> wrote:
>
> On 16/12/2014 11:23, Gergely Kiss wrote:
>>
>> Hi Rafał,
>>
>> please allow me to comment on your 2nd point as I was the one who
>> recently published the patch to make extroot functionality work with
>> UBIFS.
>>
>> "It seems that if there isn't "rootfs" MTD partition,
>> then the code will look for "rootfs" UBI volume. The same applies to
>> the "rootfs_data"."
>>
>> That's correct.
>>
>> "But what if my serial flash contains "rootfs" + "rootfs_data"
>> partitions and I still want to use some UBI volume on another flash
>> (NAND one)?"
>>
>> I'm not sure I understand what you mean here. Are there any devices
>> out there with multiple flash chips on-board? As far as I know, UBI
>> cannot work on top of block devices (eg. USB flashes, SD cards), only
>> raw flash chips so I can't really imagine what exact use-case you
>> mean. Could you please clarify?
>>
>>
>> Thanks,
>> Gergely
>>
>>
>> On 16 December 2014 at 11:00, Rafał Miłecki <zajec5 at gmail.com> wrote:
>>>
>>> I've spent few hours today trying to understand extroot. I've failed :(
>>>
>>> Of course I was trying to use wiki pages:
>>> http://wiki.openwrt.org/doc/howto/extroot
>>> http://wiki.openwrt.org/doc/uci/fstab
>>>
>>> 1) Main question
>>> Is the following sentence true at all?
>>>>
>>>> The configuration of extroot is very simple and is done entirely in
>>>> /etc/config/fstab.
>>>
>>> It seems that /etc/init.d/fstab uses "block umount" and "block mount"
>>> only. I was reading the source code (fstools-2014-12-15/block.c) and
>>> it seems that "block mount" doesn't really handle extroot at all.
>>>
>>> I think some kind of extroot support is provided in "block extroot",
>>> but I don't fully understand it. It seems to be looking for partitions
>>> "rootfs" and then "rootfs_data" ignoring whatever is set in
>>> /etc/config/fstab. If "mount extroot" is really supposed to be used,
>>> is there any way to point some external device (without MTD
>>> partitions) as extroot? I got confused.
>>>
>>> 2) UBI and UBIFS support
>>>
>>> I guess it's too new to be documented and I don't understand it much
>>> from the code. It seems that if there isn't "rootfs" MTD partition,
>>> then the code will look for "rootfs" UBI volume. The same applies to
>>> the "rootfs_data".
>>> But what if my serial flash contains "rootfs" + "rootfs_data"
>>> partitions and I still want to use some UBI volume on another flash
>>> (NAND one)?
>>>
>>> --
>>> Rafał
>>
>> _______________________________________________
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>> openwrt-devel at lists.openwrt.org
>> https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
>
>
> Hi,
>
>   I think this is where this discussion started and Rafal explains a bit
> more about the hardware:
> https://lists.openwrt.org/pipermail/openwrt-devel/2014-December/029717.html
>
> Regards,
>   Flavio
> _______________________________________________
> openwrt-devel mailing list
> openwrt-devel at lists.openwrt.org
> https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
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