[dpdk-dev] [PATCH] doc: Add known issue for iommu and igb_uio
Sergio Gonzalez Monroy
sergio.gonzalez.monroy at intel.com
Fri Dec 12 11:41:24 CET 2014
Known issue regarding iommu/VT-d and igb_uio on Linux kernel version
3.15 to 3.17 where unbinding the device from the driver removes the 1:1
mapping for the device on the iommu resulting in memory access errors.
Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy at intel.com>
---
doc/guides/rel_notes/known_issues.rst | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/doc/guides/rel_notes/known_issues.rst b/doc/guides/rel_notes/known_issues.rst
index 8ef654a..72bd0de 100644
--- a/doc/guides/rel_notes/known_issues.rst
+++ b/doc/guides/rel_notes/known_issues.rst
@@ -1026,3 +1026,35 @@ Stopping the port does not down the link on Intel® 40G ethernet controller
| Driver/Module | Poll Mode Driver (PMD) |
| | |
+--------------------------------+--------------------------------------------------------------------------------------+
+
+Devices bound to igb_uio with VT-d enabled do not work on Linux* kernel 3.15-3.17
+---------------------------------------------------------------------------------
+
++--------------------------------+--------------------------------------------------------------------------------------+
+| Title | Devices bound to igb_uio with VT-d enabled do not work on Linux* kernel 3.15-3.17 |
+| | |
++================================+======================================================================================+
+| Reference # | IXA00373938 |
+| | |
++--------------------------------+--------------------------------------------------------------------------------------+
+| Description | When VT-d is enabled (iommu=pt intel_iommu=on), devices are 1:1 mapped. |
+| | In the Linux* kernel unbinding devices from drivers removes that mapping which |
+| | result in IOMMU errors. |
+| | |
++--------------------------------+--------------------------------------------------------------------------------------+
+| Implication | Devices will not be allowed to access memory. |
+| | |
++--------------------------------+--------------------------------------------------------------------------------------+
+| Resolution/ Workaround | Use earlier or later kernel versions, or avoid driver binding on boot by |
+| | blacklisting the driver modules. |
+| | ie. in the case of ixgbe, we can pass the kernel command line option: |
+| | modprobe.blacklist=ixgbe |
+| | This way we do not need to unbind the device to bind it to igb_uio. |
+| | |
++--------------------------------+--------------------------------------------------------------------------------------+
+| Affected Environment/ Platform | Linux* systems with kernel versions 3.15 to 3.17 |
+| | |
++--------------------------------+--------------------------------------------------------------------------------------+
+| Driver/Module | igb_uio module |
+| | |
++--------------------------------+--------------------------------------------------------------------------------------+
--
1.9.3
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