[ovs-dev] [PATCH] INSTALL.DPDK: Mention issue with QEMU v2.4.0 & dpdkvhostuser

Ciara Loftus ciara.loftus at intel.com
Thu Oct 29 11:50:55 UTC 2015

Currently when using QEMU v2.4.0+, two (or more) dpdkvhostuser ports
cannot be unbound from the kernel driver in the guest without causing
the ovs-vswitchd process to crash. Document this limitation.

Signed-off-by: Ciara Loftus <ciara.loftus at intel.com>
 INSTALL.DPDK.md | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/INSTALL.DPDK.md b/INSTALL.DPDK.md
index 7bf110c..01963e9 100644
@@ -891,6 +891,16 @@ Restrictions:
     core count of the system to be less than or equal to 64 when using an XL710
     interface with DPDK.
+  vHost and QEMU v2.4.0+:
+  - For versions of QEMU v2.4.0 and later, it is currently not possible to
+    unbind more than one dpdkvhostuser port from the guest kernel driver without
+    causing the ovs-vswitchd process to crash. If this is a requirement for your
+    use case, it is recommended to use a version of QEMU between v2.2.0 and
+    v2.3.1 (inclusive). This problem will likely be resolved in Open vSwitch at
+    a later date, when the next release of DPDK is available and integrated.
+    Note: The QEMU commit ID that breaks compatibility is
+    294ce717e0f212ed0763307f3eab72b4a1bdf4d0.
 Bug Reporting:

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