Support vlan_group workaround implemented in XenServer kernels.

[sliver-openvswitch.git] / utilities / ovs-vlan-bugs.man

diff --git a/utilities/ovs-vlan-bugs.man b/utilities/ovs-vlan-bugs.man
new file mode 100644 (file)
index 0000000..bdca8fc
--- /dev/null
+++ b/utilities/ovs-vlan-bugs.man
@@ -0,0 +1,17 @@
+.IP \(bu
+When NICs use VLAN stripping on receive they must pass a pointer to a
+\fBvlan_group\fR when reporting the stripped tag to the networking
+core.  If no \fBvlan_group\fR is in use then some drivers just drop
+the extracted tag.  Drivers are supposed to only enable stripping if a
+\fBvlan_group\fR is registered but not all of them do that.
+.
+.IP \(bu
+Some drivers size their receive buffers based on whether a
+\fBvlan_group\fR is enabled, meaning that a maximum size packet with a
+VLAN tag will not fit if no \fBvlan_group\fR is configured.
+.
+.IP \(bu
+On transmit, some drivers expect that VLAN acceleration will be used
+if it is available, which can only be done if a \fBvlan_group\fR is
+configured.  In these cases, the driver may fail to parse the packet
+and correctly setup checksum offloading or TSO.