Re: dual head r128

[Geert Uytterhoeven <geert@linux-m68k.org>]

On Fri, 13 Oct 2000, Benjamin Herrenschmidt wrote:
> >But you can fixup all pci_dev's so bus 0 takes 0x00000-0x0fffff, bus 1 takes
> >0x10000-0x1ffff, and so on. ioportremap() finds out the bus by looking at the
> >region.
> >
> >I/O space is not limited to 64 kB on non-ia32, we can use the full size of an
> >unsigned long.
> >
> >Legacy I/O mappings (`I have legacy lp0 on bus 0 and legacy lp1 on bus
> 1') can
> >be sorted out in ioportremap() as well.
>
> Ok, If I follow you correctly, that mean that if we have, for example,
> bus 1 set to 0x10000-0x1ffff, ioportremap() would return, for an address
> in this range, the address + bus_io_base - 0x10000. At least on Macs,
> AFAIK, we have only 64k or 128k of IOs available.

Right.

After that `#define inb	readb' etc. and almost all overhead is gone.

And if you want to map legacy VGA I/O to bus X, you can handle this in
ioportremap(). Since ioportremap() is called only once, the complexity there
isn't of much importance.

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


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