Re: [PATCH 2.6.28-rc3] x86: make CONFIG_SWIOTLB configurable

[FUJITA Tomonori]

On Tue, 04 Nov 2008 20:28:52 +0400
Constantin Baranov <const@xxxxxxxx> wrote:

> Make it possible to enable individually the CONFIG_SWIOTLB option.
> This is useful for Intel x86_64 systems without DMAR support.
> 
> Signed-off-by: Constantin Baranov <const@xxxxxxxx>
> ---
> Tested on my system based on Gigabyte GA-EP45-DS3 mainboard
> (P45 chipset) with 8 GiB of RAM.
> Currently I need to enable either CONFIG_GART_IOMMU or
> CONFIG_AMD_IOMMU for proper work. Both are AMD specific.
> When the patch applied, just CONFIG_SWIOTLB is sufficient.
> 
>  arch/x86/Kconfig |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> --- linux-2.6.28-rc3/arch/x86/Kconfig	2008-11-04 17:32:29.846408880 +0400
> +++ linux-2.6.28-rc3-swiotlb/arch/x86/Kconfig	2008-11-04 18:11:47.796408084 +0400
> @@ -566,7 +566,9 @@ config AMD_IOMMU
>  
>  # need this always selected by IOMMU for the VIA workaround
>  config SWIOTLB
> -	bool
> +	bool "Support for software bounce buffers"
> +	depends on X86_64 && EXPERIMENTAL
> +	default n
>  	help
>  	  Support for software bounce buffers used on x86-64 systems
>  	  which don't have a hardware IOMMU (e.g. the current generation

IMHO, it's better to always enable SWIOTLB for X86_64 (the description
is a bit misleading; even with a hardware IOMMU, SWIOTLB is
necessary).
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