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To: Alan Cox <>
Subject: Re: ISA
From: Geert Uytterhoeven <>
Date: Wed, 19 Dec 2001 15:06:32 +0100 (MET)
Cc: "Maciej W. Rozycki" <>, Jun Sun <>,, Linux/MIPS Development <>
In-reply-to: <>
On Wed, 19 Dec 2001, Alan Cox wrote:
> > You must _not_ use readb()/writeb() and friends with ISA memory space!
> > You must use isa_readb()/isa_writeb() and friends!
> Linus is saying the reverse. Drivers are moving away from isa_
> > But for memory accesses, ISA memory space is not necessarily at `address 0'.
> ioremap uses ookies, its up to yoyu what you hide in the cookie from an ISA
> ioremap

OK, so I can check for < 16 MB in ioremap(), and readb() and friends will
handle it fine. You're not supposed to call ioremap() for real RAM anyway, so
there's no ambiguity.

But what about request_mem_region() and friends? How can I distinguish between
ISA memory and the first 16 MB of RAM (or ROM, or whatever my board has there)?

Or am I not supposed to let those things show up in /proc/iomem?



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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