diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86_64/Kconfig | 10 | ||||
| -rw-r--r-- | arch/x86_64/kernel/pci-dma.c | 28 |
2 files changed, 12 insertions, 26 deletions
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig index 02dd39457bc..a55382a1bb4 100644 --- a/arch/x86_64/Kconfig +++ b/arch/x86_64/Kconfig @@ -458,8 +458,8 @@ config IOMMU 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 AMD Athlon64/Opteron/Turion/Sempron GART - based IOMMU and a software bounce buffer based IOMMU used on Intel - systems and as fallback. + based hardware IOMMU and a software bounce buffer based IOMMU used + on Intel systems and as fallback. The code is only active when needed (enough memory and limited device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified too. @@ -496,6 +496,12 @@ config CALGARY_IOMMU_ENABLED_BY_DEFAULT # need this always selected by IOMMU for the VIA workaround config SWIOTLB bool + help + Support for software bounce buffers used on x86-64 systems + which don't have a hardware IOMMU (e.g. the current generation + of Intel's x86-64 CPUs). Using this PCI devices which can only + access 32-bits of memory can be used on systems with more than + 3 GB of memory. If unsure, say Y. config X86_MCE bool "Machine check support" if EMBEDDED diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c index 683b7a5c1ab..651ccfb0669 100644 --- a/arch/x86_64/kernel/pci-dma.c +++ b/arch/x86_64/kernel/pci-dma.c @@ -223,30 +223,10 @@ int dma_set_mask(struct device *dev, u64 mask) } EXPORT_SYMBOL(dma_set_mask); -/* iommu=[size][,noagp][,off][,force][,noforce][,leak][,memaper[=order]][,merge] - [,forcesac][,fullflush][,nomerge][,biomerge] - size set size of iommu (in bytes) - noagp don't initialize the AGP driver and use full aperture. - off don't use the IOMMU - leak turn on simple iommu leak tracing (only when CONFIG_IOMMU_LEAK is on) - memaper[=order] allocate an own aperture over RAM with size 32MB^order. - noforce don't force IOMMU usage. Default. - force Force IOMMU. - merge Do lazy merging. This may improve performance on some block devices. - Implies force (experimental) - biomerge Do merging at the BIO layer. This is more efficient than merge, - but should be only done with very big IOMMUs. Implies merge,force. - nomerge Don't do SG merging. - forcesac For SAC mode for masks <40bits (experimental) - fullflush Flush IOMMU on each allocation (default) - nofullflush Don't use IOMMU fullflush - allowed overwrite iommu off workarounds for specific chipsets. - soft Use software bounce buffering (default for Intel machines) - noaperture Don't touch the aperture for AGP. - allowdac Allow DMA >4GB - nodac Forbid DMA >4GB - panic Force panic when IOMMU overflows -*/ +/* + * See <Documentation/x86_64/boot-options.txt> for the iommu kernel parameter + * documentation. + */ __init int iommu_setup(char *p) { iommu_merge = 1; |