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-rw-r--r--Documentation/Intel-IOMMU.txt37
1 files changed, 20 insertions, 17 deletions
diff --git a/Documentation/Intel-IOMMU.txt b/Documentation/Intel-IOMMU.txt
index 49585b6e1ea2..9dae6b47e398 100644
--- a/Documentation/Intel-IOMMU.txt
+++ b/Documentation/Intel-IOMMU.txt
@@ -1,3 +1,4 @@
+===================
Linux IOMMU Support
===================
@@ -9,11 +10,11 @@ This guide gives a quick cheat sheet for some basic understanding.
Some Keywords
-DMAR - DMA remapping
-DRHD - DMA Remapping Hardware Unit Definition
-RMRR - Reserved memory Region Reporting Structure
-ZLR - Zero length reads from PCI devices
-IOVA - IO Virtual address.
+- DMAR - DMA remapping
+- DRHD - DMA Remapping Hardware Unit Definition
+- RMRR - Reserved memory Region Reporting Structure
+- ZLR - Zero length reads from PCI devices
+- IOVA - IO Virtual address.
Basic stuff
-----------
@@ -33,7 +34,7 @@ devices that need to access these regions. OS is expected to setup
unity mappings for these regions for these devices to access these regions.
How is IOVA generated?
----------------------
+----------------------
Well behaved drivers call pci_map_*() calls before sending command to device
that needs to perform DMA. Once DMA is completed and mapping is no longer
@@ -82,14 +83,14 @@ in ACPI.
ACPI: DMAR (v001 A M I OEMDMAR 0x00000001 MSFT 0x00000097) @ 0x000000007f5b5ef0
When DMAR is being processed and initialized by ACPI, prints DMAR locations
-and any RMRR's processed.
+and any RMRR's processed::
-ACPI DMAR:Host address width 36
-ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed90000
-ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed91000
-ACPI DMAR:DRHD (flags: 0x00000001)base: 0x00000000fed93000
-ACPI DMAR:RMRR base: 0x00000000000ed000 end: 0x00000000000effff
-ACPI DMAR:RMRR base: 0x000000007f600000 end: 0x000000007fffffff
+ ACPI DMAR:Host address width 36
+ ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed90000
+ ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed91000
+ ACPI DMAR:DRHD (flags: 0x00000001)base: 0x00000000fed93000
+ ACPI DMAR:RMRR base: 0x00000000000ed000 end: 0x00000000000effff
+ ACPI DMAR:RMRR base: 0x000000007f600000 end: 0x000000007fffffff
When DMAR is enabled for use, you will notice..
@@ -98,10 +99,12 @@ PCI-DMA: Using DMAR IOMMU
Fault reporting
---------------
-DMAR:[DMA Write] Request device [00:02.0] fault addr 6df084000
-DMAR:[fault reason 05] PTE Write access is not set
-DMAR:[DMA Write] Request device [00:02.0] fault addr 6df084000
-DMAR:[fault reason 05] PTE Write access is not set
+::
+
+ DMAR:[DMA Write] Request device [00:02.0] fault addr 6df084000
+ DMAR:[fault reason 05] PTE Write access is not set
+ DMAR:[DMA Write] Request device [00:02.0] fault addr 6df084000
+ DMAR:[fault reason 05] PTE Write access is not set
TBD
----