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-rw-r--r--share/man/man4/vtnet.453
1 files changed, 39 insertions, 14 deletions
diff --git a/share/man/man4/vtnet.4 b/share/man/man4/vtnet.4
index b6f10ddd87cb..fd41b36882a6 100644
--- a/share/man/man4/vtnet.4
+++ b/share/man/man4/vtnet.4
@@ -22,7 +22,7 @@
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.Dd August 21, 2025
+.Dd September 30, 2025
.Dt VTNET 4
.Os
.Sh NAME
@@ -54,6 +54,20 @@ TCP segmentation offload (TSO), TCP large receive offload (LRO),
hardware VLAN tag stripping/insertion features, a multicast hash filter,
as well as Jumbo Frames (up to 9216 bytes), which can be
configured via the interface MTU setting.
+.Pp
+Two flavors of TCP LRO are supported:
+Hardware TCP LRO, which is performed by the host providing TCP segments larger
+than the MTU to the guest, and Software TCP LRO, which is performed by the
+network stack of the guest processing TCP segments in an optimized way.
+Only one flavour of TCP LRO should be used.
+Since hardware TCP LRO can have bad interactions with IP forwarding and
+software TCP LRO mitigates several drawbacks of hardware TCP LRO, the default
+setting is to disable hardware TCP LRO.
+See the loader tunable
+.Va hw.vtnet. Ns Ar X Ns Va .lro_disable .
+.Pp
+TCP/UDP receive checksum offload cannot be configured independently for IPv4
+and IPv6.
Selecting an MTU larger than 1500 bytes with the
.Xr ifconfig 8
utility configures the adapter to receive and transmit Jumbo Frames.
@@ -84,14 +98,16 @@ field of the structure
.Vt struct virtio_net_hdr .
It also marks the checksum as being correct in the mbuf packet header.
The default value is 0.
+This tunable is deprecated and will be removed in
+.Fx 16 .
.It Va hw.vtnet.tso_disable
.It Va hw.vtnet. Ns Ar X Ns Va .tso_disable
This tunable disables TCP segmentation offloading.
The default value is 0.
.It Va hw.vtnet.lro_disable
.It Va hw.vtnet. Ns Ar X Ns Va .lro_disable
-This tunable disables large receive offload.
-The default value is 0.
+This tunable disables hardware TCP LRO.
+The default value is 1.
.It Va hw.vtnet.mq_disable
.It Va hw.vtnet. Ns Ar X Ns Va .mq_disable
This tunable disables multiqueue.
@@ -115,11 +131,11 @@ This tunable sets the number of RX segments processed in one pass.
The default value is 1024.
.It Va hw.vtnet.lro_entry_count
.It Va hw.vtnet. Ns Ar X Ns Va .lro_entry_count
-This tunable sets the software LRO entry count.
+This tunable sets the software TCP LRO entry count.
The default value is 128, the minimum value is 8.
.It Va hw.vtnet.lro_mbufq_depth
.It Va hw.vtnet. Ns Ar X Ns Va .lro_mbufq_depth
-This tunable sets the depth of the software LRO mbuf queue.
+This tunable sets the depth of the software TCP LRO mbuf queue.
The default value is 0.
.It Va hw.vtnet.altq_disable
This tunable disables ALTQ support, allowing the use of multiqueue instead.
@@ -127,7 +143,6 @@ This option applies to all interfaces.
The default value is 0.
.El
.Sh TRANSMIT QUEUE STATISTICS
-.Bl -tag -width "xxxxxx"
For each transmit queue of each interface the following read-only statistics
are provided:
.Bl -tag -width "xxxxxx"
@@ -154,7 +169,14 @@ The number of times the receive interrupt handler was rescheduled.
.It Va dev.vtnet. Ns Ar X Ns Va .rxq Ns Ar Y Ns Va .host_lro
The number of times TCP large receive offload was performed.
.It Va dev.vtnet. Ns Ar X Ns Va .rxq Ns Ar Y Ns Va .csum_failed
-Currently not used.
+The number of times a packet with a request for receive or transmit checksum
+offloading was received and this request failed.
+The different reasons for the failure are counted by
+.Va dev.vtnet. Ns Ar X Ns Va .rx_csum_inaccessible_ipproto ,
+.Va dev.vtnet. Ns Ar X Ns Va .rx_csum_bad_ipproto ,
+.Va dev.vtnet. Ns Ar X Ns Va .rx_csum_bad_ethtype ,
+and
+.Va dev.vtnet. Ns Ar X Ns Va .rx_csum_bad_offset .
.It Va dev.vtnet. Ns Ar X Ns Va .rxq Ns Ar Y Ns Va .csum
The number of times receive checksum offloading for UDP or TCP was performed.
.It Va dev.vtnet. Ns Ar X Ns Va .rxq Ns Ar Y Ns Va .ierrors
@@ -214,18 +236,21 @@ over all receive queues of the interface.
The sum of
.Va dev.vtnet. Ns Ar X Ns Va .rxq Ns Ar Y Ns Va .csum_failed
over all receive queues of the interface.
-.It Va dev.vtnet. Ns Ar X Ns Va .rx_csum_bad_proto
-Currently unused.
+.It Va dev.vtnet. Ns Ar X Ns Va .rx_csum_inaccessible_ipproto
+The number of times a packet with a request for receive or transmit checksum
+offloading was received where the IP protocol was not accessible.
.It Va dev.vtnet. Ns Ar X Ns Va .rx_csum_bad_offset
-Currently unused.
-.It Va dev.vtnet. Ns Ar X Ns Va .rx_csum_bad_ipproto
-Currently unused.
-.It Va dev.vtnet. Ns Ar X Ns Va .rx_csum_bad_ethtype
The number of times fixing the checksum required by
.Va hw.vtnet.fixup_needs_csum
or
.Va hw.vtnet. Ns Ar X Ns Va .fixup_needs_csum
-was attempted for a packet with an EtherType other than IPv4 or IPv6.
+was attempted for a packet where the csum is not located in the first mbuf.
+.It Va dev.vtnet. Ns Ar X Ns Va .rx_csum_bad_ipproto
+The number of times a packet with a request for receive or transmit checksum
+offloading was received where the IP protocol was neither TCP nor UDP.
+.It Va dev.vtnet. Ns Ar X Ns Va .rx_csum_bad_ethtype
+The number of times a packet with a request for receive or transmit checksum
+offloading was received where the EtherType was neither IPv4 nor IPv6.
.It Va dev.vtnet. Ns Ar X Ns Va .rx_mergeable_failed
The number of times receiving a mergable buffer failed.
.It Va dev.vtnet. Ns Ar X Ns Va .rx_enq_replacement_failed