[U-Boot] [PATCH RFC] add CONFIG_BOOTCOUNT_LIMIT for MCF5445x

[Wolfgang Wegner]

Dear Wolfgang Denk,

On Fri, Apr 23, 2010 at 09:25:35PM +0200, Wolfgang Denk wrote:
> Dear Wolfgang Wegner,
> 
> In message <1272026324-18566-1-git-send-email-w.wegner at astro-kom.de> you wrote:
> > This patch adds bootcount for Freescale MCF5445x. Two registers of
> > eDMA transfer control descriptors (TCD[1]) are used because these
> > are unused by linux kernel (freescale LTIB linux-2.6.25) and were
> > tested to keep their contents across resets.
> ...
> > +#ifdef CONFIG_BOOTCOUNT_LIMIT
> > +/*
> > + * We use transfer descriptor registers as a persistent storage
> > + * across resets. This was tested on a MCF54455.
> > + * Neither U-Boot nor the stock LTIB kernel seem to use
> > + * TCD[1], so it should be safe at least until application
> > + * start.
> 
> This is not sufficent, then. The bootcounter requires to be reset from
> User Space, i. e. _after_ the application has been succesfully
> started. If application start messes with the value, this fails to
> work.

sorry, my wording was not correct.
What I meant was that no device driver in stock kernel uses these
registers, so the only possibility for them to get used is if the
init system or application loads some non-standard drivers.

Regards,
Wolfgang