Re: dual head r128

From: Geert Uytterhoeven (
Date: Fri Oct 13 2000 - 11:25:29 EST

On Thu, 12 Oct 2000, Benjamin Herrenschmidt wrote:
> Note to linux-kenrel readers: This discussion is the Nth attempt to find
> a solution to handle both legacy IOs and PCI IOs on machines with several
> IO busses memory mapped at different locations in the CPU space.

> Linus: Would you accept this change now ?
> #define ISA_PORT(n) (n)
> And change to _all_ drivers doing legacy IOs to use that in their in/out
> macros ?


> My "pet" solution would be to have all legacy drivers request an IO base
> this way
> base = isa_get_IO_base(legacy_addr);
> The isa_get_IO_base function could then be "tweaked" to recognize known
> legacy addresses and return different bases. (There might still be
> problems with VGA vs. parallell, I don't know x86 world well enough to be
> sure).

Or, more general, treat [PCI] I/O space similar to [PCI] memory space. Just
like we must use ioremap() for memory space:

    cookie = ioremap(memory_space_address, size);
    x = readb(cookie+offset);

we could have ioportremap() for I/O space:

    cookie = ioportremap(io_space_address, size);
    x = inb(cookie+offset);

On PC, ioportremap(x) would evaluate to (x). On other platforms, we can do
whatever we want.



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

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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