Re: IO issues vs. multiple busses

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On Sat, 3 Mar 2001, Grant Grundler wrote:
> Benjamin Herrenschmidt wrote:
> > Additionally, the same problem is true for ISA memory, when it exist
> > obviously.
>
> Really? I expected ISA memory to look like reguler uncacheable memory
> and the drivers would simply dereference the address. But I'm not an
> expert on how ISA busses work...

Nope, it's like PCI memory, but different. You have to use isa_readb() and
friends to access it.

While ISA I/O space and PCI I/O space are the same on many machines with memory
mapped I/O (with a size limitation for ISA I/O), ISA memory space and PCI
memory space are different. Cfr. on my CHRP LongTrail:

| callisto$ cat /proc/iomem
| 00000000-08000000 : RAM
| c0000000-f6ffffff : GG2 PCI mem
| c0000000-c0000fff : ATI Technologies Inc 3D Rage I/II 215GT [Mach64 GT]
| c1000000-c107ffff : Apple Computer Inc. Hydra Mac I/O
| c1080000-c108007f : Digital Equipment Corporation DECchip 21041 [Tulip Pass 3]
| c1080000-c108007f : eth0
| c2000000-c2ffffff : ATI Technologies Inc 3D Rage I/II 215GT [Mach64 GT]
| c2000000-c2ffffff : atyfb
| c3000000-c30000ff : Symbios Logic Inc. (formerly NCR) 53c875
| c3001000-c3001fff : Symbios Logic Inc. (formerly NCR) 53c875
| c4000000-c7ffffff : S3 Inc. 86c764/765 [Trio32/64/64V+]
| f7000000-f7ffffff : GG2 ISA mem
| f70e0000-f70e7fff : NVRAM
| f8000000-f8ffffff : GG2 PCI I/O
| fec00000-fec7ffff : GG2 PCI cfg
| ff000000-ff7fffff : ROM exp
| fff80000-ffffffff : Flash ROM
| callisto$

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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• Next message: Michal Jaegermann: "Re: [Slightly OT] x86 PROM project"
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