From ced3c42c9fcba049ec9c76c8461ac194cafb20ba Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 6 Oct 2013 11:45:20 +0200 Subject: [PATCH] x86/iommu: Clean up the CONFIG_GART_IOMMU config option a bit Improve the explanation of this config option. Cc: Andi Kleen Cc: Borislav Petkov Link: http://lkml.kernel.org/n/tip-gUMmysvsbl3mccbyf6olmxqg@git.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/Kconfig | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index c9d2b81ea310..7081958a32fb 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -760,15 +760,21 @@ config GART_IOMMU select SWIOTLB depends on X86_64 && PCI && AMD_NB ---help--- - Support for full DMA access of devices with 32bit memory access only - on systems with more than 3GB. This is usually needed for USB, - sound, many IDE/SATA chipsets and some other devices. - Provides a driver for the older AMD Athlon64/Opteron/Turion/Sempron GART - based hardware IOMMU. - Newer systems typically have a better AMD IOMMU. - The code is only active when needed (enough memory and limited - device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified - too. + Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron + GART based hardware IOMMUs. + + The GART supports full DMA access for devices with 32-bit access + limitations, on systems with more than 3 GB. This is usually needed + for USB, sound, many IDE/SATA chipsets and some other devices. + + Newer systems typically have a modern AMD IOMMU, supported via + the CONFIG_AMD_IOMMU=y config option. + + In normal configurations this driver is only active when needed: + there's more than 3 GB of memory and the system contains a + 32-bit limited device. + + If unsure, say Y. config CALGARY_IOMMU bool "IBM Calgary IOMMU support"