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

From: Russell King - ARM Linux
Date: Thu Nov 10 2011 - 17:57:47 EST


On Mon, Nov 07, 2011 at 04:16:58PM +0000, Catalin Marinas wrote:
> This patch adds the ARM_LPAE and ARCH_PHYS_ADDR_T_64BIT Kconfig entries
> allowing LPAE support to be compiled into the kernel.
>
> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> ---
> arch/arm/Kconfig | 2 +-
> arch/arm/mm/Kconfig | 17 +++++++++++++++++
> 2 files changed, 18 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 44789ef..885c04e 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1959,7 +1959,7 @@ endchoice
>
> config XIP_KERNEL
> bool "Kernel Execute-In-Place from ROM"
> - depends on !ZBOOT_ROM
> + depends on !ZBOOT_ROM && !ARM_LPAE
> help
> Execute-In-Place allows the kernel to run from non-volatile storage
> directly addressable by the CPU, such as NOR flash. This saves RAM
> diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
> index 67f75a0..d289cdb 100644
> --- a/arch/arm/mm/Kconfig
> +++ b/arch/arm/mm/Kconfig
> @@ -629,6 +629,23 @@ config IO_36
>
> comment "Processor Features"
>
> +config ARM_LPAE
> + bool "Support for the Large Physical Address Extension"
> + depends on MMU && CPU_V7
> + help
> + Say Y if you have an ARMv7 processor supporting the LPAE page
> + table format and you would like to access memory beyond the
> + 4GB limit. The resulting kernel image will not run on
> + processors without the LPA extension.
> +
> + If unsure, say N.
> +
> +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.
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