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From: "tone.zhang" <tone.zhang@arm.com>
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Cc: gavin.hu@arm.com, bruce.richardson@intel.com, bluca@debian.org,
roszenrami@gmail.com, Honnappa.Nagarahalli@arm.com,
stephen@networkplumber.org, nd@arm.com
Date: Wed, 26 Sep 2018 13:08:47 +0800
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Subject: [dpdk-dev] [PATCH v6] doc: Clarify IOMMU usage with
"uio_pci_generic" kernel module
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If the devices used for DPDK are bound to the "uio_pci_generic" kernel
module, the IOMMU should be disabled in order not to break the IO
transmission because of the virtual / physical address mapping.
The patch clarifies the IOMMU configurations on both x86_64 and arm64
systems.
Signed-off-by: tone.zhang <tone.zhang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Rami Rosen <roszenrami@gmail.com>
Acked-by: Gavin Hu <Gavin.Hu@arm.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Luca Boccassi <bluca@debian.org>
---
doc/guides/linux_gsg/linux_drivers.rst | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/doc/guides/linux_gsg/linux_drivers.rst b/doc/guides/linux_gsg/linux_drivers.rst
index 371a817..8da6a31 100644
--- a/doc/guides/linux_gsg/linux_drivers.rst
+++ b/doc/guides/linux_gsg/linux_drivers.rst
@@ -48,6 +48,13 @@ be loaded as shown below:
``vfio-pci`` kernel module rather than ``igb_uio`` or ``uio_pci_generic``.
For more details see :ref:`linux_gsg_binding_kernel` below.
+.. note::
+
+ If the devices used for DPDK are bound to the ``uio_pci_generic`` kernel module,
+ please make sure that the IOMMU is disabled or passthrough. One can add
+ ``intel_iommu=off`` or ``amd_iommu=off`` or ``intel_iommu=on iommu=pt``in GRUB
+ command line on x86_64 systems, or add ``iommu.passthrough=1`` on arm64 system.
+
Since DPDK release 1.7 onward provides VFIO support, use of UIO is optional
for platforms that support using VFIO.
--
2.7.4