Re: [MiNT] 040/060 MMU tree builder

[Michael Schwingen <rincewind@discworld.dascon.de>]

On Mon, May 17, 1999 at 02:26:29AM +0000, Odd Skancke wrote:
> 
> 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

Correct. However, TOS should turn off the MMU in the reset handler, and that
means that your remapped memory will be gone. Hooking into the reset vector
should be too early in the startup process to change that, IIRC.

>  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

Correct. You can init and enable the MMU with a 1:1 mapping from the auto
folder - however, it is too late then to remap RAM, since GEMDOS is already
initialized.

> 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.

Um - the hades TOS does not turn off the MMU? sure? How is that supposed to
work on warm/cold boots?

cu
Michael
-- 
Michael Schwingen, Ahornstrasse 36, 52074 Aachen