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-rw-r--r--Documentation/x86/x86_64/boot-options.txt5
-rw-r--r--arch/x86/kernel/pci-dma.c4
2 files changed, 2 insertions, 7 deletions
diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
index 341588ec4e29..8d109ef67ab6 100644
--- a/Documentation/x86/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
@@ -236,11 +236,6 @@ IOMMU (input/output memory management unit)
nomerge Don't do scatter-gather (SG) merging.
noaperture Ask the IOMMU not to touch the aperture for AGP.
noagp Don't initialize the AGP driver and use full aperture.
- allowdac Allow double-address cycle (DAC) mode, i.e. DMA >4GB.
- DAC is used with 32-bit PCI to push a 64-bit address in
- two cycles. When off all DMA over >4GB is forced through
- an IOMMU or software bounce buffering.
- nodac Forbid DAC mode, i.e. DMA >4GB.
panic Always panic when IOMMU overflows.
calgary Use the Calgary IOMMU if it is available
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index b65b0d7072f1..b523414bc323 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -122,9 +122,9 @@ static __init int iommu_setup(char *p)
if (!strncmp(p, "forcesac", 8))
pr_warn("forcesac option ignored.\n");
if (!strncmp(p, "allowdac", 8))
- forbid_dac = 0;
+ pr_warn("allowdac option ignored.\n");
if (!strncmp(p, "nodac", 5))
- forbid_dac = 1;
+ pr_warn("nodac option ignored.\n");
if (!strncmp(p, "usedac", 6)) {
forbid_dac = -1;
return 1;