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[ts-7000] Re: ts-7000 in unattended embedded service

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Subject: [ts-7000] Re: ts-7000 in unattended embedded service
From: "Jesse Off" <>
Date: Tue, 16 Aug 2005 15:09:01 -0000
--- In  "nivekengg" <> wrote:
> After reading this list and experimenting with my board, two 
> questions regarding use of the ts-7000 as an embedded machine...
> 
> 1. autologins. How can I provide an auto-login for the case where
I 
> do not have a connection to a serial monitor and keyboard. I would 
> like the system to boot at powerup, login, and begin execution of
my 
> applications/scripts automatically with no user input.

You just will want to put your applications/scripts in the startup
script /etc/rc.d/rcS.sysinit

There is no such thing as "auto-login" in Linux.  The closest thing
would be to bypass the normal initialization procedure (which
invokes the getty and login on the serial terminal) with your own
program by passing an init=/myprogram from the kernel startup
command line.

> 
> 2. Power shutdowns and file corruption. In reading the list, it 
> appears that filesystem corruption is a common problem after power 
> cycling. My current application centers around data logging with
just 
> the keypad and lcd interface for a minimal interface. The system 
> should not require user interaction to boot and run from powerup,
and 
> ideally shut down gracefully upon power removal. Datalogging to 
> either comnpact flash, or more ideally USB memory stick is
required 
> to allow easy removal of media and copy to windows machines (this 
> means vfat fs). 
> Can anyone recommend a best practice in this scenario to minimize 
> risk of filesystem corruption?
> One thought is to implement a delay timer to leave the ts7000
powered 
> for long enough to shut down gracefully but what is the preferred 
> shutdown sequence to minimize risk of filesystem corruption? Is 
> poweroff the right solution?

VFAT is not a good filesystem for guaranteed surviveability on
asynchronous shutdown/poweroff.  You can increase your chances by
mounting with the "sync" option, but its not clear if Linux actually
implements this correctly in the VFAT code (it may just ignore it).

IIRC, EXT3 implements a meta-data journal that should guarantee that
the filesystem doesn't trash itself, but you can still end up
loosing bits of the files that were being written to at time of the
unclean shutdown.  I know EXT2/EXT3 correctly honor the 'sync' flag,
which if used should reduce (but not eliminate) your chances of
filesystem corruption by an order of magnitude.  The only time your
filesystem is vulnerable to corruption on unclean shutdown is when a
process is writing to a file.

You may also have complications with Linux in that you may not just
arbitrarily unplug the USB device from a running system where it has
been mounted.  It first has to be unmounted from software before
being unplugged.

//Jesse Off




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