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x86/iommu: Clean up the CONFIG_GART_IOMMU config option a bit
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Improve the explanation of this config option.

Cc: Andi Kleen <ak@linux.intel.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/n/tip-gUMmysvsbl3mccbyf6olmxqg@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Ingo Molnar committed Oct 6, 2013
1 parent 38901f1 commit ced3c42
Showing 1 changed file with 15 additions and 9 deletions.
24 changes: 15 additions & 9 deletions arch/x86/Kconfig
Original file line number Diff line number Diff line change
Expand Up @@ -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"
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