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 --- Documentation/kernel-parameters.txt | 7 +++++++ drivers/pci/intel-iommu.c | 7 ++++++- 2 files changed, 13 insertions(+), 1 deletion(-) Index: linux-2.6.22-rc4-mm2/Documentation/kernel-parameters.txt =================================================================== --- linux-2.6.22-rc4-mm2.orig/Documentation/kernel-parameters.txt 2007-06-18 15:45:46.000000000 -0700 +++ linux-2.6.22-rc4-mm2/Documentation/kernel-parameters.txt 2007-06-18 15:45:46.000000000 -0700 @@ -788,6 +788,13 @@ 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 Index: linux-2.6.22-rc4-mm2/drivers/pci/intel-iommu.c =================================================================== --- linux-2.6.22-rc4-mm2.orig/drivers/pci/intel-iommu.c 2007-06-18 15:45:46.000000000 -0700 +++ linux-2.6.22-rc4-mm2/drivers/pci/intel-iommu.c 2007-06-19 13:09:06.000000000 -0700 @@ -53,6 +53,7 @@ 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); @@ -70,6 +71,10 @@ 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, ","); @@ -1557,7 +1562,7 @@ 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 { -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/