diff options
| -rw-r--r-- | Documentation/x86_64/boot-options.txt | 4 | ||||
| -rw-r--r-- | arch/x86_64/kernel/pci-dma.c | 18 |
2 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt index 4303e0c12476..e97a4c8fe6ea 100644 --- a/Documentation/x86_64/boot-options.txt +++ b/Documentation/x86_64/boot-options.txt @@ -199,6 +199,10 @@ IOMMU 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 + When off all DMA over >4GB is forced through an IOMMU or bounce + buffering. + nodac Forbid DMA >4GB swiotlb=pages[,force] diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c index 4dcb671bd19f..225e19941b67 100644 --- a/arch/x86_64/kernel/pci-dma.c +++ b/arch/x86_64/kernel/pci-dma.c @@ -170,8 +170,20 @@ void dma_free_coherent(struct device *dev, size_t size, } EXPORT_SYMBOL(dma_free_coherent); +static int forbid_dac __read_mostly; + int dma_supported(struct device *dev, u64 mask) { +#ifdef CONFIG_PCI + if (mask > 0xffffffff && forbid_dac > 0) { + + + + printk(KERN_INFO "PCI: Disallowing DAC for device %s\n", dev->bus_id); + return 0; + } +#endif + if (dma_ops->dma_supported) return dma_ops->dma_supported(dev, mask); @@ -231,6 +243,8 @@ EXPORT_SYMBOL(dma_set_mask); 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 */ __init int iommu_setup(char *p) { @@ -267,6 +281,10 @@ __init int iommu_setup(char *p) iommu_merge = 0; if (!strncmp(p, "forcesac",8)) iommu_sac_force = 1; + if (!strncmp(p, "allowdac", 8)) + forbid_dac = 0; + if (!strncmp(p, "nodac", 5)) + forbid_dac = -1; #ifdef CONFIG_SWIOTLB if (!strncmp(p, "soft",4)) |