Upgrading cramfs root file system while running (DENX wrote that is not possible)

Tolunay Orkun betatester at orkun.us
Sun Apr 23 05:53:09 EST 2006

Antonio Di Bacco wrote:
> Little bit off topic:
> I decided to adopt a different strategy, the sw download web page will contain 
> a java applet that will act as a tftp server, then the board will be rebooted 
> and an environment variable will instruct the u-boot to tftp the new software 
> from the applet. What do you think? I know that applets cannot read local 
> files on the PC, unless they have a valid certificate but the user should 
> trust me.
> Bye,
> Antonio.

If this approach hits a roadblock for some reason (user resistance, 
firewall issues with tftp etc.), think about the following...

During the update you can use a small ram based file system (tempfs) 
holding everything you need, kill all unneeded processes, fill your ram 
based file system. Once this ram file system is filled you will 
pivot_root to it making it new root fs and proceed to update from it. 
Once update is down you can reboot.

I have not done this so it is very likely there are some details that I 
cannot foresee at this very moment.

Best regards,

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