Re: Atari TT (next)

Geert Uytterhoeven
2012-01-08T19:53:08Z

Hi Michael,

On Sun, Jan 8, 2012 at 20:21, Michael Schmitz <schmitzmic@googlemail.com> wrote:
>>> ST-RAM (breaking the above assumption). Something similar is done for Amiga
>>> chip RAM - exactly how does the chip RAM situation differ, Geert? Is chip
>>> RAM being claimed by mem_init or is it being left aside?
>>
>> Chip RAM is different in that Linux (unlike AmigaOS) doesn't use it as
>> system RAM.
>> Being on the Zorro II bus (first 16 MiB), it's slow on most machines and doesn't
>> support RMW cycles (needed for page tables) on Zorro III-capable machines.
>> In general, we don't use Z2 RAM as system memory on Z3 capable machines.
>
> But is its physical address lower than the kernel segment's, as in this case?

Yes, Zorro II space is the first 16 MiB.
But it's handled completely separately from system RAM.
Its mapping is set up in mmu_init_amiga() in head.S.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds