[Avila] fail over mechanism strategy (Avila IXP425 ) - need suggestion

[Bhanu Prakash Adhikari]

Dacker, Thanks a lot.
=0D

-----Original Message-----
From: David Acker [mailto:dacker at roinet.com]=0D
Sent: Thursday, February 22, 2007 9:59 PM
To: Avila
Subject: Re: [Avila] fail over mechanism strategy (Avila IXP425 ) - need
suggestion

Bhanu Prakash Adhikari wrote:
> Folks,
>=0D
> I'm working on a fail over mechanism on Avila board with IXP425
> processor.
>=0D
> My new requirement is to have a robust fail over mechanism - for
example
> - when the CF card or the image it has got corrupted for some reason,
I
> must have a light thin version (may be uClinux or snapgear) of image
> should be loaded on the board and continue working with the new
> (uClinux/snapgear) image. With the thin image the CF will be rewritten
> or reformatted with new image.
>=0D
> My strategy is to have uClinux/snapgear image on the inbuilt flash and
> would be invoked when CF is corrupted.
>=0D

We have a setup with a failsafe kernel and production kernel and a=0D
failsafe ramdisk and a production ramdisk all on the built in flash.  It

is a busybox based setup with just the other commands we need.  The=0D
failsafe's only job in life is to allow for USB based upgrading and is=0D
this a stipped down kernel and ramdisk.  When we do an upgrade we change

redboot's startup config to point to the failsafe area.  Only after we=0D
have confirmed that the new flash is totally written correctly do we=0D
switch the boot line to the production flash.
To change redboot's startup line from linux use fconfig from=0D
http://andrzejekiert.ovh.org/software.html.en

The mailing list website appears to be down, so I will reproduce the=0D
notes I had about this from some time ago.

The fconfig author states that it will not work for flash stored=0D
settings but I believe he just hit a setup issue...the partitions are=0D
not setup the way the MTD layer wants them by the default redboot so=0D
that they are not writable.  It puts the "RedBoot config" and the "FIS=0D
directory" into one flash block.  The MTD code wants all partitions to=0D
end on a flash block.  It is pretty easy to fix though.  First, Redboot=0D
has a config parameter to control it.  Turn off:
CYGSEM_REDBOOT_FLASH_COMBINED_FIS_AND_CONFIG

Next, I patched redboot to size the "RedBoot config" so that it was at=0D
least a flash block.  MTD will not let you write to partitions that end=0D
before the flash block does.

Checkout the attached patch...it fixes both issues.  Note, you will have

  to fis init after this.

You will also need to use flash_unlock to open the flash.

After that you can use fconfig to change to boot script.
-Ack

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