Re: isa_read/write not available on ppc - solution suggestions ??

[Linus Torvalds]

On Tue, 1 May 2001, Russell King wrote:
>
> Talking around this issue, is there any chance of getting the
> official use of the first parameter to ioremap documented in
> Documentation/IO-mapping.txt please?  There appears to be
> confusion as to whether it is:
>
> a) PCI bus address
> b) CPU untranslated address

It's neither.

It's a cookie that you can do arithmetic off and pass on to the
readx/writex, and nothing more. You cannot make any assumptions at all
about what it means.

In particular, you can _not_ assume that it is a PCI bus address ("WHICH
bus?") and you can absolutely not assume that it is a CPU address (many
CPU's do not "memory map" PCI at all).

                Linus

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