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Re: ISA

To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Subject: Re: ISA
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Thu, 20 Dec 2001 14:14:29 +0100 (MET)
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, Jun Sun <jsun@mvista.com>, jim@jtan.com, Linux/MIPS Development <linux-mips@oss.sgi.com>
In-reply-to: <Pine.GSO.3.96.1011220135315.3556A-100000@delta.ds2.pg.gda.pl>
Sender: owner-linux-mips@oss.sgi.com
On Thu, 20 Dec 2001, Maciej W. Rozycki wrote:
> On Wed, 19 Dec 2001, Geert Uytterhoeven wrote:
> > 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)?
> 
>  Well, as I stated in another mail (but in another thread, I think) you
> may try request_mem_region(virt_to_phys(ioremap(...))), especially as you
> really want to reserve an area in the CPU's physical address space and not
> in the bus's one.

So we must update all existing drivers that use ISA memory space anyway.

IMHO still better to add isa_request_mem_region() while we're at it, so we can
solve this in an arch-specific way. Ia32 can still say

    #define isa_request_mem_region      request_mem_region

> > Or am I not supposed to let those things show up in /proc/iomem?
> 
>  I think the appearance is not the point here.  The point is to prevent a
> driver from accessing an already occupied area. 

Right.

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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