Geert Uytterhoeven geert at linux-m68k.org
Fri Mar 19 10:25:32 GMT 2004

On Fri, 19 Mar 2004, Kars de Jong wrote:
> That does leave the fact that we need to solve ioremap() of ISA memory
> on m68k. I thing the best way to do it is to make it behave like on
> other architectures: if an ioremap() is done on an address < 16MB,
> assume it's ISA. This does pose a nice problem on the Amiga which has
> non-ISA resources in this range. On the other hand, that range is
> always-mapped, so ioremap() and the drivers using those resources could
> be made to detect this (call ioremap() with the always-mapped virtual
> address instead of the physical address in drivers/video/amifb.c and
> others).

Woops, we have Zorro II space in the first 16 MB. Although you don't have to
use z_ioremap() on it, it's allowed. This can be fixed by not mapping ioremap()
to __ioremap() directly, but using some translation layer.

See, that's one big problem with ISA memory space everywhere: assuming it
starts at address 0 everywhere causes problems. The same with
request_mem_region(): how to distinguish between a region in PCI memory space,
ISA memory space, or Zorro memory space?

The same problem exists on PPC: my (LongTrail) ISA memory space is not at
address 0, I have real RAM there, so request_mem_region() of VGA memory will
fail. We do need isa_request_mem_region() (zillionth try to tell people that).



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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

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