Re: [MiNT] 040/060 MMU tree builder

[Odd Skancke <oskancke@online.no>]

Hi, Michael!

On Fri, 14 May 1999, Michael Schwingen wrote:

> On Thu, May 13, 1999 at 08:16:40PM +0000, Odd Skancke wrote:
> 
> >  As for the usability of this tool, I think everyone with a 040 or 060
> > would benefit from using it, as it is very configurable.
> 
> Um - just a note: how do you want to start this *before* TOS initializes its
> internal memory management stuff?

TOS sets up the memory according to the values found at phystop.w,
memtop.w, and _memtop.w, right? This means that one can change those
variables and jump trough the reset vector. Then TOS should set up memory
based on those variables. If this is not possible, then I don't know how
to do it.... yet :)

 Well, as it does now, it sets up the mmu-tree, loads the URP and SRP with
the same tree address (with 1:1 mapping), sets up the TTRs and turn on the
MMU. This works very well on the Hades TOS. I think that if it turns out
to be a problem with TOS changing these settings, all other mapping than
1:1 will be impossible (cause the tree will then have to be initialize at
a later stage), unless TOS itself can setup a tree and enable the MMU
according to some kind of info file. Well.. to be fully honest, I have
been trying to map the area between $0x00e00000 and $0x01000000 to the
last two megabytes in the TT-RAM logical addressing space and I have not
been successful, altho when I think about it now, there are numerous
things I didn't try. But, I know that TOS does not touch the MMU settings
during startup. Unless it turn off the mmu and turns it back on for each
program it executes in the autofolder, but that is highly unlikely.
Besides, the MMU have to be ON for MiNT to enable MP when it boots, right?
I haven't tried MP yet either, tho ;-)

 If you have any info you think I need, please let me have it ,-) I'm no
expert on this area - new turf for me.



Odd Skancke - ozk@atari.org