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

[Stefan Eletzhofer]

Hi,

Am 21.04.2006 um 23:32 schrieb Antonio Di Bacco:

> 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.

nice idea IMHO. Is that applet available somewhere? That would surely  
fit my needs
(and others probably, too).

Cheers,
Stefan.

>
> Bye,
> Antonio.
>
> On Friday 21 April 2006 22:23, Wolfgang Denk wrote:
>> In message <200604210853.32860.david.jander at protonic.nl> you wrote:
>>> What do you mean with "something bad could happen"?
>>
>> System crashes.
>>
>>> The only thing I can think of is pulling the power plug while  
>>> flash is
>>> being erased or written. What else could go wrong?
>>
>> The kernel may try to (re-) load some pages of a  running  executable
>> or  library  which  is  no  longer  available  (at  least  not at the
>> addresses where they used to be). The kernel will either stumble over
>> what it believes to be a corrupted file system,  or  load  the  wrong
>> data -> kaboom.
>>
>>> We do the following: system running from read-only jffs2 partition.
>>> Sometimes that partition is remounted read-write and single files  
>>> are
>>> replaced, but in some occasions we need to upgrade the whole fs.  
>>> In that
>>> case a CGI lodas the image into a ramdisk, and the upgrade  
>>> process is
>>> started. For upgrade,
>>
>> You *have* to unmount the old file system here.
>>
>>> partition, and then "dd" again to copy the image. At that point no
>>> critical flash-read access should be requested since dd is  
>>> already in
>>> cache (it's
>>
>> The kernel might reload any page of any running executable or  
>> library.
>>
>> Best regards,
>>
>> Wolfgang Denk
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