AW: contributing a failsafe update meachanism for FIS from within ecos applications

["Neundorf, Alexander" <Alexander dot Neundorf at jenoptik dot com>]

> -----Ursprüngliche Nachricht-----
> Von: Andrew Lunn [mailto:andrew@lunn.ch]
> Gesendet: Montag, 18. Oktober 2004 16:50
> An: Neundorf, Alexander
> Cc: ecos-devel@sources.redhat.com
> Betreff: Re: contributing a failsafe update meachanism for FIS from
> within ecos applications
> 
> > > You should have CDL to control where the second flash 
> block is. Its
> > > bad to assume its the next block. 
> > 
> > Really ?
> > IMO it would be ok if the blocks are directly one after the 
> other. One could think of it as a fis dir twice as big as 
> before containing two copies of this fis dir.
> 
> But what about people who want to add this to an existing project and
> there only free blocks in flash are somewhere else.

Ok.

...
> I would think about trying to use the existing format so that it
> remains backward compatible. I think about add a dummy image to the
> fis list. Dummy in that it start and length are 0. But the name would
> be something like. "Fis Valid*" The sting is 16 charactors long. So
> there are 5 unused charactors after the \0. You could put your magic
> numbers there. This will probably be backward compatible with old
> redboots. They will just see it as a normal entry with some junk after
> the end of the string. Where i showed "*" in the sting, if you think
> carefully about ASCII and the binary representation, you might be able
> to come up with a set of charactors which differ by resetting 1's to
> give some sort of meaningful mapping to the state of the FIS
> directory.

Ok, I'll post a modified patch which uses "$Magic[01]" as "magic number" in the next days, with "$Magic0" for the fis table 0 and "$Magic1" for fis table 1. This leaves 8 bytes room for the valid_flag and the version_count.

Bye
Alex