RE: [Xen-devel] allocating AGP aperture memory

["Langsdorf, Mark" <mark.langsdorf@xxxxxxx>]

> > At some point I need to be able to remap the actual, physical
> > e0000000 address range into something locally addressable.  
> > ioremap_cache is failing, though that might be because of the 
> > page reserve collision above.
> 
> I haven't looked at the code, but why would you want to map 
> the GART aperture into kernel virtual address space? The CPU 
> shouldn't need to access stuff through the remapped region -- 
> its PCI DMAs that should be using it.

You're right, I don't really want to do that, but I got
inadvertantly sidetracked into thinking I needed AGP
support working.  Fortunately, I don't.

However, if I don't have AGP support working, I need
to program the Northbridge registers with the 
physical address of the GATT (see init_k8_gatt() in 
arch/xen/x86_64/kernel/pci-gart.c).
Just doing a __pa() obviously doesn't return 
meaningful data, which is to be expected.  How should
dom0 go about getting it?

-Mark Langsdorf
AMD, Inc.



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