Re: ioremap_nocache problem?

From: Stephen C. Tweedie (sct@redhat.com)
Date: Fri Jan 26 2001 - 05:43:46 EST


Hi,

On Thu, Jan 25, 2001 at 11:53:01AM -0600, Timur Tabi wrote:
>
> > As in an MMIO aperture? If its MMIO on the bus you should be able to
> > just call ioremap with the bus address. By nature of it being outside
> > of real ram, it should automatically be uncached (unless you've set an
> > MTRR over that region saying otherwise).
>
> It's not outside of real RAM. The device is inside real RAM (it sits on the
> DIMM itself), but I need to poke through the entire 4GB range to see how it
> responds.

kmap() is designed for that, not ioremap(). Is it absolutely
essential that your mapping is uncached? If so, extending kmap() to
support kmap_nocache() would seem to make a lot more sense than using
ioremap(): kmap is there for temporarily poking around in high memory,
whereas ioremap is really intended to be used for persistent maps.

--Stephen
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