Re: [ECOS] RedBoot porting

[Grant Edwards <grante@visi.com>]

On Tue, Jan 09, 2001 at 10:09:23AM -0700, Gary Thomas wrote:

> > That's one of my concerns about running RedBoot from ROM: If I
> > run RedBoot from ROM, then I can't allow the application to use
> > any of the virtual vector stuff.  The application needs to be
> > able to write to flash, and if RedBoot is running from flash
> > it's not going to be available during a flash burn.
> 
> This is only a problem if interrupts can occur while you're
> actually writing/erasing the flash (not a good idea in my
> mind).  

I suppose it would be simpler to just shut down the whole thing
for several seconds, but that's not a good option.  It's a
multitasking system: even though one task is busy burning
something into flash, the other tasks (miscellaneous network
stuff, background diagnostics, data transfer, web server) all
need to keep running.

I might have to pause the web server since it's pages are in
flash and I don't want to copy them into RAM.  That's
sub-optimal, but tolerable.  The other tasks have to keep
running.

> Otherwise, what would the flash access functions be doing
> calling virtual vector stuff?

Printing status info on the diagnostic output channel mainly.
My flash burn routine displays diagnostic info as it burns
flash.  Other tasks that are still running also need to display
status output, and I presume the network stack may need to call
virtual vector stuff for debug purposes.

-- 
Grant Edwards
grante@visi.com