Re: [PATCH v8 16/16] ARM: LPAE: Add the Kconfig entries

[Catalin Marinas]

On Thu, Nov 10, 2011 at 10:57:37PM +0000, Russell King - ARM Linux wrote:
> On Mon, Nov 07, 2011 at 04:16:58PM +0000, Catalin Marinas wrote:
> > +config ARCH_PHYS_ADDR_T_64BIT
> > +	def_bool ARM_LPAE
> > +
> > +config ARCH_DMA_ADDR_T_64BIT
> > +	def_bool ARM_LPAE
> > +
> 
> I still say this shouldn't depend on the host page table format.  LPAE
> itself has nothing to do with whether 64-bit DMA addresses are supported
> by the system.

So we could change this to:

config ARCH_DMA_ADDR_T_64BIT
	depends on ARM_LPAE

and let platforms select it.

The x86 approach is to have another HIGHMEM64G config option for
systems with more than 4GB of RAM and ARCH_DMA_ADDR_T_64BIT is selected
automatically. But this comes under the assumption that there is a 1:1
mapping between phys and bus addresses.

-- 
Catalin
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