Another try at the run-from-Flash issue for MPC8xx/MBX/custom

Richard Hendricks ra6353 at
Fri Mar 31 06:39:19 EST 2000

  Do you have the I-Cache enabled when decompressing?  What about
disabling serialization? (Set ICTRL to 0x7)

Doug Rogers wrote:
> I, too, would like to run from Flash. The question for me isn't speed,
> isn't cost, nor EMI effects. It is simply a matter of size. We have a
> very small area in which to squeeze the parts, and the best we could do
> is 32M RAM and 16M ROM. Our application code is in the 10M range (text
> only, even after chopping over half of it out!), but it is expected to
> grow. So for us it's not really a matter of cost or (running) speed,
> since the Flash runs fast enough for our purposes.
> As another constraint, our card needs to be able to run very soon after
> power-up. I've hacked the LynxOS startup monitor to detect either gzip'd
> or bzip2'd KDI's. I've timed the decompression of our smaller test image
> and it takes over 40 seconds on a 40MHz MBX860 board. That's too slow.
> We could live with 20, perhaps, but not much more than that. For now I
> boot my images over the network since our MBX board has only 4M Flash.
> It's faster than decompressing!
> With LynxOS, we're able to keep in Flash both the text sections of the
> kernel AND of all binaries on the filesystem. Wow! That allows us to put
> only the RAM disk and vector/data/bss sections into RAM. Shweet!
> I was hoping that Linux was to that point, but apparently not. Just
> having the kernel run from ROM would be helpful for now, so if anyone
> out there has done so, I'd be very appreciative of any feedback.
> Thanks!
> Doug
> --
> --_._-__-____------_--_-_-_-___-___-____-_--_-___--____-___--_-__--___-_
> Doug Rogers, ICI   | The strongest reason for the people to retain the
> V:703.893.2007x220 | right to keep and bear arms is, as a last resort,
>    | to protect themselves against tyranny in
> ___________________| Government. [Thomas Jefferson]

** Sent via the linuxppc-embedded mail list. See

More information about the Linuxppc-embedded mailing list