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-rw-r--r--drivers/pci/intel-iommu.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 05630b44dbfc..cb24defdb6d9 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -54,6 +54,7 @@ static void domain_remove_dev_info(struct dmar_domain *domain);
static int dmar_disabled;
static int __initdata dmar_map_gfx = 1;
+static int dmar_forcedac;
#define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
static DEFINE_SPINLOCK(device_domain_lock);
@@ -71,6 +72,10 @@ static int __init intel_iommu_setup(char *str)
dmar_map_gfx = 0;
printk(KERN_INFO
"Intel-IOMMU: disable GFX device mapping\n");
+ } else if (!strncmp(str, "forcedac", 8)) {
+ printk (KERN_INFO
+ "Intel-IOMMU: Forcing DAC for PCI devices\n");
+ dmar_forcedac = 1;
}
str += strcspn(str, ",");
@@ -1558,7 +1563,7 @@ static dma_addr_t __intel_map_single(struct device *dev, void *addr,
start_addr = IOVA_START_ADDR;
- if (pdev->dma_mask <= DMA_32BIT_MASK) {
+ if ((pdev->dma_mask <= DMA_32BIT_MASK) || (dmar_forcedac)) {
iova = iommu_alloc_iova(domain, addr, size, start_addr,
pdev->dma_mask);
} else {