[maemo-users] [maemo-users] Booting from MMC as a de-bricking method

From: Paule Ecimovic paule at certrex.net
Date: Wed Feb 14 13:09:23 EET 2007
Thanks Frantisek and all for your responses. I am most concerned about the 
bricking scenarios resulting from flashing a 770 to set it into R&D mode, 
where the 770 sometimes bricks after rebooting. Are there bricking scenarios 
in this reboot situation which involve corruption beyond MMC reboot? Any 
chance of hard-disk based ITOS for Nokia Internet Tablet's. I know this 
would require more power and possibly a larger footprint and many 
architectural modifications which might defeat the (nascent niche) purpose, 
but it would allow rebooting in various modes and under various privledge 
schemes without the threat of irreparable bricking.


----- Original Message ----- 
From: "Frantisek Dufka" <dufkaf at seznam.cz>
To: "Paule Ecimovic" <paule at certrex.net>
Cc: <maemo-users at maemo.org>
Sent: Tuesday, February 13, 2007 3:07 PM
Subject: Re: [maemo-users] Booting from MMC as a de-bricking method

> Paule Ecimovic wrote:
>> Hi, all
>>  Is it possible to boot from MMC (assuming one sets up this booting 
>> option by cloning the 770 on a suitably-large MMC and installing the 
>> alternate boot loader and all the rest) to recover from a bricking flash?
> Boot from mmc can help you only when the problem is in rootfs partition 
> i.e. (a bit simplistic explanation) when booting the device blue 
> progressbar on the bottom starts.
> I'm not sure what you mean by 'bricking flash' but any device reflash with 
> full firmware image removes modified initfs with boot menu and then you 
> cannot boot from mmc at all (without reflashing modified initfs back). But 
> this is not big problem because booting from mmc allows you to stop fixing 
> problems with your device by reflashing. Instead of reflashing you can 
> boot clean system and either mount broken system and fix it (if you know 
> how) or save data from it and clone your clean system to mmc and start 
> again.
>> Are there bricking scenarios from which it is not possible to recover via 
>> booting from MMC?
> Definitely yes but most things that can normally go wrong happen in 
> rootfs. Examples:
> - you install bad/incompatible package
> - you try apt-get upgrade
> - you are trying to hack startup sequence
> - device reboots in wrong moment and some system files get lost or become 
> corrupted (yes this really happens sometimes if you are unlucky)
> Frantisek 

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