Subject: cramfs and crontab timestamp

From: "hubert.loewenguth" <[email-masked]>
Date: Thu, 15 Jun 2006 17:25:37 +0200

hi to the community

I'm not sure here is the good place for my question because it's not 
related to the ppc architecture, but i try.
Here is my problem I don't understand:
I have an embended linux 2.4.20 on a 8260 ppc with a cramfs root 
file-system I use since 1 year.
Everything works fine.
During the init process, the content of the /etc directory is copy in a 
tmpfs file system and then then a tmpfs file-system is mounted on /etc 
and fill with the old content.
(thanks to that, I can replace after some files in the /etc by other 
specific files store in a little jffs part of the flash with the 
customer specific configurations /etc configuration files).

Recently, I've decided to add cron to this platform and something very 
strange appear.
My /etc/crontab file is very simple:

-----------------------------------------------
SHELL=/bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=""
HOME=/

#test of cron
* * * * * root echo date >>/tmp/essai
-----------------------------------------------

everything works fine when I boot on a nfs file-system.
But nothing is done (/tmp/essai not created) if I boot on the cramfs 
file-system.
And what is the only difference beetwen the two startup:........ the 
timestamp of the /etc/crontab (1/1/1970 for crontab coming from the cramfs)

So I try something after having boot on cramfs:
echo "#toto">>/etc/crontab

And ones  I have done this, the cron process start to work correctly, 
creating and editing the /tmp/essai.
I know that cron verify if the /etc/crontab has changed every mn, so I 
think this is the reason it works after, but why does it not see the 
first crontab file ?
It's juste like the 1/1/1970 timestamp of /etc/crontab make him 
invisible by cron.

Does anyone having an idea or having already encounter this kind of 
problem ?
I have find nothing on the web about this or a similar problem.

Thanks for any help