From 7d3b03ce7bff9d39ebaee1bb8de1968c4434b883 Mon Sep 17 00:00:00 2001 From: "Keshavamurthy, Anil S" Date: Sun, 21 Oct 2007 16:41:53 -0700 Subject: [PATCH] Intel IOMMU: Intel iommu cmdline option - forcedac Introduce intel_iommu=forcedac commandline option. This option is helpful to verify the pci device capability of handling physical dma'able address greater than 4G. Signed-off-by: Anil S Keshavamurthy Cc: Andi Kleen Cc: Peter Zijlstra Cc: Muli Ben-Yehuda Cc: "Siddha, Suresh B" Cc: Arjan van de Ven Cc: Ashok Raj Cc: "David S. Miller" Cc: Christoph Lameter Cc: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/kernel-parameters.txt | 7 +++++++ drivers/pci/intel-iommu.c | 7 ++++++- 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 8157417724..b236166783 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -781,6 +781,13 @@ and is between 256 and 4096 characters. It is defined in the file bypassed by not enabling DMAR with this option. In this case, gfx device will use physical address for DMA. + forcedac [x86_64] + With this option iommu will not optimize to look + for io virtual address below 32 bit forcing dual + address cycle on pci bus for cards supporting greater + than 32 bit addressing. The default is to look + for translation below 32 bit and if not available + then look in the higher range. io7= [HW] IO7 for Marvel based alpha systems See comment before marvel_specify_io7 in diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index 05630b44db..cb24defdb6 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 { -- 2.39.5