[ECOS] Creating eCos flash application image for AT91 EB40a Redboot

Gary D. Thomas gary.thomas@mind.be
Fri May 23 23:39:00 GMT 2003

On Fri, 2003-05-23 at 09:52, Nick Garnett wrote:
> Øyvind Harboe <oyvind.harboe@zylin.com> writes:
> > Is there a reason(other than that it isn't done yet) 
> > why the Redboot load command does not support writing to flash?
> > 
> > It seems like all the hard pieces are already done. Previously
> > I worked with a home made bootloader, and it had a load command
> > that wrote directly from serial port to flash.
> The main problem is that the load command and the flash commands are
> totally independent at present. To work the loader would have to write
> to memory through some interface that interacted with the flash
> subsystem in some way. Not impossible, but just not done this way at
> present.

Indeed, it is this way by design.  IMO loading stuff into memory
is quite distinct from writing to the FLASH.  There are times when
one wants to do one and not the other and I don't think that the 
functions should be intertwined like this.  Then there is the problem 
of reasonable ways to manage the two functions.  Some devices may
take a very long time to write - how might one throttle the incoming
data stream while this happens?  That's just one of many complications
that would be added if these functions were combined.  Another thing
is that it's a good idea to verify that the image has been correctly
downloaded before committing to FLASH - that's why there's a separate
checksum command.  This is just part of the list...

Of course, since the source is out there one is free to change it
however one wants.
Gary D. Thomas <gary.thomas@mind.be>

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