[U-Boot] request for ubifs recovery support

[Detlev Zundel]

Hi Albert,

> Le 17/11/2010 19:01, Quotient Remainder a écrit :
>> Ar Céad, 2010-11-17 ag 17:25 +0100, scríobh Albert ARIBAUD:
>>
>>> Do you mean that, in Linux, you do a power cycle without (syncing and)
>>> unmounting a file system that will be critical to properly booting later
>>> on? If so, what is the rationale behind this too-quick power cycle?
>>
>> Yes, I'm testing power-fail tolerance!  The RFS is mounted in sync mode
>> so unless I'm missing something the sync should have occurred before the
>> command prompt reappears, right?
>>
>>>
>>> Seems to me you should start by the preventive measure of avoiding the
>>> corruption in the first place (do a cp; sync; umount...) rather than
>>> relying on a curative measure of recovery attempts.
>>
>> Ideally, yes and "sync" before power-down works but that's not what
>> these tests are checking.  With the RFS not in sync mode, it works;
>> "sync" command with sync mount currently untested.
>
>
> Ok, now I understand why you do this cp-then-powercycle routine.
>
> Granted, cp on a sync mount should have finished when you get back to 
> the prompt, so that's one Linux, not U-boot, issue to dig into; but 
> anyway, if you're testing for powerfail conditions, I guess you also 
> test power-cycling in the middle of the cp, so you may end up with a 
> corrupted ubifs anyway.

Exactly.

> I guess if you or Eric know how to enable ubifs recovery in u-boot, the 
> simplest course of action is to just go ahead and try it -- but I still 
> think the cp+powercycle issue is caused purely in Linux and should be 
> fixed there.

If we use UBIFS in U-Boot then we need to be prepared for whatever state
the UBIFS is in on powerup.  Tolerance to power failures is one of the
topmost featues of this fs (number 4 according to its webpage :) so
U-Boot not having this property feels like a let down.

Actually I wonder why nobody complained earlier about that...

Cheers
  Detlev

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