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SubjectRe: IO issues vs. multiple busses
On Sat, 3 Mar 2001, Benjamin Herrenschmidt wrote:
> With those two simple functions, we could at least
>
> - Have vgacon disable itself when there's no ISA memory (that can be
^^^^^^^^^^
> handled by
> reserving the region and thus preventing request_region from working
^^^^^^^^^^^^^^
Do you mean request_mem_region()?

> too, well,
> but that scheme would also simplify the various more/less hacked
> macros used
> on all non-x86 archs to access the VGA memory).

request_mem_region() for ISA memory is another problem point. The few drivers
that use it seem to assume that the ISA memory base is 0. This won't work on
non-PC machines, since ISA memory may be somewhere else in the address space,
and more important, there already may be something different at address 0,
which breaks request_mem_region(). On a PC the first 16 MB of RAM (with some
holes at e.g. 0xa0000) overlap with ISA memory space, but not on other
architectures.

For ioremap() we have a hack on PPC (PReP/CHRP) that adds isa_mem_base if the
bus address to map falls in the first 16 MB area, but this cannot work for
request_mem_region(). I do have my full memory map (RAM) marked in /proc/iomem.

So once again I vote for the introduction of
isa_{request,release}_mem_region(), just like we already have isa_readb() and
friends.

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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