Re: [PATCH 4/4] x86, gart: Make sure GART does not map physmemabove 1TB

[Roedel, Joerg]

On Mon, Apr 18, 2011 at 10:46:24AM -0400, H. Peter Anvin wrote:
> On 04/18/2011 06:45 AM, Joerg Roedel wrote:
> > The GART can only map physical memory below 1TB. Make sure
> > the gart driver in the kernel does not try to map memory
> > above 1TB.
> 
> Where does this limit come from?

>From the hardware. A GART PTE is only 32 bits in size so that it cannot
be expanded. The physical address bits 32-39 are mapped 11:4 in the PTE.
This can not be architecturally expanded to more than 40 physical bits.

Regards,

	Joerg

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