Re: ioremap_nocache problem?

[Timur Tabi <ttabi@interactivesi.com>]

** Reply to message from Jeff Hartmann <jhartmann@valinux.com> on Thu, 25 Jan
2001 10:47:13 -0700


> 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.

> Look at the functions agp_generic_free_gatt_table and 
> agp_generic_create_gatt_table in agpgart_be.c (drivers/char/agp).  They 
> do the ioremap_nocache on real ram for the GATT/GART table.

Unfortunately, the memory they remap is allocated:

table = (char *) __get_free_pages(GFP_KERNEL, page_order);

...

CACHE_FLUSH();
agp_bridge.gatt_table = ioremap_nocache(virt_to_phys(table), (PAGE_SIZE * (1 <<
page_order)));
CACHE_FLUSH();

I've searched high and low for examples of code that does what I do, and I
can't find any.


-- 
Timur Tabi - ttabi@interactivesi.com
Interactive Silicon - http://www.interactivesi.com

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