[ECOS] ARM port architecture questions

Gary Thomas gthomas@ecoscentric.com
Mon Nov 25 11:42:00 GMT 2002

On Mon, 2002-11-25 at 12:36, Patrick Doyle wrote:
> >
> > Getting the MMU going should take you less time than it took to write
> > this explanation :-)  Just look at (i.e. copy) the setup code from a
> > working platform, such as the iPAQ or one of the ARM9 platforms.  Fill
> > in the specifics in the hal_mmu_init() function and you're done.
> >
> I'll drop this now, since the consensus seems to be "use the MMU", but,
> being a newcomer to the ARM architecture, how do I know that the MMU on one
> part will be identical to that on another part.  The answer is "I (wpd)
> don't know this."  So, I'll go an look at the iPAQ (since I want to learn
> about that anyway) or one of the ARM9 platforms, find a data sheet that
> documents the MMU on that platform, parse through the MMU setup, wonder
> about why you chose to do that that way, wonder if it makes sense for me to
> choose to do it the same way or not, find out that my MMU is slightly
> different, etc...
> If I were using a StrongARM, I would start with the iPAQ and not bother with
> these questions.

Modulo very small differences (which I've never seen matter),
they simply *are* the same, at least for the new chips.  It
certainly makes sense for you to try and understand how the
MMU works, but my experience is that the code that we have
in place is very easy to tailor (just change the numbers to
match your specifics) and will work with no additional tweaks.

Of course, should you find this not to be the case, we'd love
to hear about it!

Gary Thomas                  |
eCosCentric, Ltd.            |  
+1 (970) 229-1963            |  eCos & RedBoot experts
gthomas@ecoscentric.com      |
http://www.ecoscentric.com/  |

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