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Subject: Re: [PATCH] Add quick erase format option
From: Stefani Seibold <stefani@seibold.net>
To: David Woodhouse <dwmw2@infradead.org>
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Date: Mon, 09 Aug 2010 10:52:54 +0200
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Am Montag, den 09.08.2010, 09:37 +0100 schrieb David Woodhouse:
> On Mon, 2010-08-09 at 09:25 +0100, stefani@seibold.net wrote:
> > From: Stefani Seibold <stefani@seibold.net>
> > 
> > This patch add a quick format option which skips erasing of already erased
> > flash blocks. This is useful for first time production environments where
> > the flash arrived erased.
> > 
> > Signed-off-by: Stefani Seibold <stefani@seibold.net> 
> 
> This scares me, given the lengths we had to go to in JFFS2 to cope with
> blocks which *look* like they're erased, but which actually start losing
> data as soon as you start writing to them because the erase didn't
> complete.
> 

I know the drawback. This is why it is only an option which must be
enabled. And in most use cases there is a subsequent ubimkvol, which
will fail if the flash is not correct initialized.

Flash are normally delivered erased. So this save in our production
environment (Nokia Siemens Networks) about 5 minutes per device (256 MB
NOR CFI Flash).

The old JFFS2 was very fast to install the first time on a flash, it was
only a simple mount of the MTD partition. 

Which the quick format option i have now only a slightly first time
installation overhead compared to JFFS2. Without this option the
overhead is more than 5 minutes.

- Stefani