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From: Anatoly Burakov <anatoly.burakov@intel.com>
To: dev@dpdk.org
Cc: thomas@monjalon.net
Subject: [dpdk-dev] [PATCH 4/4] doc: add VFIO troubleshooting section
Date: Tue, 10 Nov 2020 18:09:50 +0000
Message-ID: <8125335fc1a508b216ddf013fe83907277d3d5f0.1605031542.git.anatoly.burakov@intel.com> (raw)
In-Reply-To: <7d1840b4184bf363e3b9ddaff0683f13b324078a.1605031542.git.anatoly.burakov@intel.com>
In-Reply-To: <7d1840b4184bf363e3b9ddaff0683f13b324078a.1605031542.git.anatoly.burakov@intel.com>

There are common problems with VFIO that get asked over and over on the
mailing list. Document common problems with VFIO and how to fix them or
at least figure out what went wrong.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 doc/guides/linux_gsg/linux_drivers.rst | 43 ++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/doc/guides/linux_gsg/linux_drivers.rst b/doc/guides/linux_gsg/linux_drivers.rst
index 4148602a63..e30d91ea78 100644
--- a/doc/guides/linux_gsg/linux_drivers.rst
+++ b/doc/guides/linux_gsg/linux_drivers.rst
@@ -247,3 +247,46 @@ To restore device ``82:00.0`` to its original kernel binding:
 .. code-block:: console
 
     ./usertools/dpdk-devbind.py --bind=ixgbe 82:00.0
+
+Troubleshooting VFIO
+--------------------
+
+In certain situations, using ``dpdk-devbind.py`` script to bing a device to VFIO
+driver will fail. The first place to check is the kernel messages:
+
+.. code-block:: console
+
+    # dmesg | tail
+    ...
+    [ 1297.875090] vfio-pci: probe of 0000:31:00.0 failed with error -22
+    ...
+
+In most cases, the "error -22" indicates that the VFIO subsystem couldn't be
+enabled because there is no IOMMU support. To check whether the kernel has been
+booted with correct parameters, one can check the kernel command-line:
+
+.. code-block:: console
+
+    # cat /proc/cmdline
+
+Please refer to earlier sections on how to configure kernel parameters correctly
+for your system.
+
+If the kernel is configured correctly, one also has to make sure that the BIOS
+configuration has virtualization features (such as Intel® VT-d). There is no
+standard way to check if the platform is configured correctly, so please check
+with your platform documentation to see if it has such features, and how to
+enable them.
+
+In certain distributions, default kernel configuration is such that the no-IOMMU
+mode is disabled altogether at compile time. This can be checked in the boot
+configuration of your system:
+
+.. code-block:: console
+
+    # cat /boot/config-$(uname -r) | grep NOIOMMU
+    # CONFIG_VFIO_NOIOMMU is not set
+
+If ``CONFIG_VFIO_NOIOMMU`` is not enabled in the kernel configuration, VFIO
+driver will not support the no-IOMMU mode, and other alternatives (such as UIO
+drivers) will have to be used.
-- 
2.17.1

  parent reply	other threads:[~2020-11-10 18:10 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-10 18:09 [dpdk-dev] [PATCH 1/4] doc: move VFIO driver to be first Anatoly Burakov
2020-11-10 18:09 ` [dpdk-dev] [PATCH 2/4] doc: reword VFIO and UIO Linux GSG section Anatoly Burakov
2020-11-10 18:09 ` [dpdk-dev] [PATCH 3/4] doc: add VFIO no-IOMMU " Anatoly Burakov
2020-11-10 18:09 ` Anatoly Burakov [this message]
2020-11-18 15:37 ` [dpdk-dev] [PATCH v2 1/4] doc: move VFIO driver to be first Anatoly Burakov
2020-11-18 18:24   ` David Marchand
2020-11-19 11:04     ` Burakov, Anatoly
2020-11-19 11:32   ` [dpdk-dev] [PATCH v3 " Anatoly Burakov
2020-11-23 17:22     ` Ferruh Yigit
2020-11-19 11:32   ` [dpdk-dev] [PATCH v3 2/4] doc: reword VFIO and UIO Linux GSG section Anatoly Burakov
2020-11-19 11:32   ` [dpdk-dev] [PATCH v3 3/4] doc: add VFIO no-IOMMU " Anatoly Burakov
2020-11-27 15:47     ` Bruce Richardson
2020-11-19 11:32   ` [dpdk-dev] [PATCH v3 4/4] doc: add VFIO troubleshooting section Anatoly Burakov
2020-11-27 15:30     ` Thomas Monjalon
2020-11-27 15:57       ` Burakov, Anatoly
2020-11-27 15:49     ` Bruce Richardson
2020-11-27 16:29     ` Kevin Traynor
2020-11-27 17:27       ` Thomas Monjalon
2020-11-18 15:37 ` [dpdk-dev] [PATCH v2 2/4] doc: reword VFIO and UIO Linux GSG section Anatoly Burakov
2020-11-18 15:37 ` [dpdk-dev] [PATCH v2 3/4] doc: add VFIO no-IOMMU " Anatoly Burakov
2020-11-18 15:37 ` [dpdk-dev] [PATCH v2 4/4] doc: add VFIO troubleshooting section Anatoly Burakov

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