Upgrading cramfs root file system

Wojciech Kromer wojciech.kromer at dgt.com.pl
Fri Apr 21 16:42:01 EST 2006

Dnia 2006-04-20 22:18, Użytkownik White napisał:
> make it easy: if you start an application which do the flash and after
> this a reset.. nothing should happen. I do it that way.
> the application resist completly in RAM .. and all important libs are
> in RAm or in Filesystem Cache.
> It's only important that you pretend any Application from accessing
> Datafiles or start of new application ...
> Alternativly, you can put it in a reserved RAM Area ( mark it not
> usable by Linux) and put a Flash Code in your Bootloader (U-boot?)
> after a reset....
> But overwrite a cramfs works for me on >100 times without problems.

Problems with changing cramfs  and reboot may vary depending on changes 
made to filesystem.
You can't even call reboot, bacause it's not in the prevoius location 
after changing flash.

> Am Thu, 20 Apr 2006 21:54:45 +0200 schrieb Antonio Di Bacco
> <antonio.dibacco at aruba.it> :
>> Yes you are right, it is not a good idea to overwrite working cramfs 
>> filesystem. But what happens if I download the new cramfs plus kernel in RAM, 
>> do a checksum and then, completely in kernel mode, disabling all the 
>> interrupts, I write to flash? No process could complain that I am overwriting 
>> because no one is executing.
Maybe such feature should be added to MTD code.
But disabling interrupts may cause watchdog reset in most embedded 

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