Differential D52684 Diff 163132 share/man/man4/vtnet.4

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	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL			.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY			.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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	.\" SUCH DAMAGE.			.\" SUCH DAMAGE.
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	.Dd September 26, 2025			.Dd September 30, 2025
	.Dt VTNET 4			.Dt VTNET 4
	.Os			.Os
	.Sh NAME			.Sh NAME
	.Nm vtnet			.Nm vtnet
	.Nd VirtIO Ethernet driver			.Nd VirtIO Ethernet driver
	.Sh SYNOPSIS			.Sh SYNOPSIS
	To compile this driver into the kernel,			To compile this driver into the kernel,
	place the following lines in your			place the following lines in your
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	.Pp			.Pp
	If the hypervisor advertises the appropriate features, the			If the hypervisor advertises the appropriate features, the
	.Nm			.Nm
	driver supports TCP/UDP checksum offload for both transmit and receive,			driver supports TCP/UDP checksum offload for both transmit and receive,
	TCP segmentation offload (TSO), TCP large receive offload (LRO),			TCP segmentation offload (TSO), TCP large receive offload (LRO),
	hardware VLAN tag stripping/insertion features, a multicast hash filter,			hardware VLAN tag stripping/insertion features, a multicast hash filter,
	as well as Jumbo Frames (up to 9216 bytes), which can be			as well as Jumbo Frames (up to 9216 bytes), which can be
	configured via the interface MTU setting.			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.
				timo.voelker_fh-muenster.deUnsubmitted Not Done Inline Actions The user does not have the option to use both, right? I would replace the should with a can. timo.voelker_fh-muenster.de: The user does not have the option to use both, right? I would replace the should with a can.
				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			TCP/UDP receive checksum offload cannot be configured independently for IPv4
	and IPv6.			and IPv6.
	Selecting an MTU larger than 1500 bytes with the			Selecting an MTU larger than 1500 bytes with the
	.Xr ifconfig 8			.Xr ifconfig 8
	utility configures the adapter to receive and transmit Jumbo Frames.			utility configures the adapter to receive and transmit Jumbo Frames.
	.Pp			.Pp
	For more information on configuring this device, see			For more information on configuring this device, see
	.Xr ifconfig 8 .			.Xr ifconfig 8 .
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	This tunable is deprecated and will be removed in			This tunable is deprecated and will be removed in
	.Fx 16 .			.Fx 16 .
	.It Va hw.vtnet.tso_disable			.It Va hw.vtnet.tso_disable
	.It Va hw.vtnet. Ns Ar X Ns Va .tso_disable			.It Va hw.vtnet. Ns Ar X Ns Va .tso_disable
	This tunable disables TCP segmentation offloading.			This tunable disables TCP segmentation offloading.
	The default value is 0.			The default value is 0.
	.It Va hw.vtnet.lro_disable			.It Va hw.vtnet.lro_disable
	.It Va hw.vtnet. Ns Ar X Ns Va .lro_disable			.It Va hw.vtnet. Ns Ar X Ns Va .lro_disable
	This tunable disables large receive offload.			This tunable disables hardware TCP LRO.
	The default value is 0.			The default value is 1.
	.It Va hw.vtnet.mq_disable			.It Va hw.vtnet.mq_disable
	.It Va hw.vtnet. Ns Ar X Ns Va .mq_disable			.It Va hw.vtnet. Ns Ar X Ns Va .mq_disable
	This tunable disables multiqueue.			This tunable disables multiqueue.
	The default value is 0.			The default value is 0.
	.It Va hw.vtnet.mq_max_pairs			.It Va hw.vtnet.mq_max_pairs
	.It Va hw.vtnet. Ns Ar X Ns Va .mq_max_pairs			.It Va hw.vtnet. Ns Ar X Ns Va .mq_max_pairs
	This tunable sets the maximum number of transmit and receive queue pairs.			This tunable sets the maximum number of transmit and receive queue pairs.
	Multiple queues are only supported when the Multiqueue feature is negotiated.			Multiple queues are only supported when the Multiqueue feature is negotiated.
	This driver supports a maximum of 8 queue pairs.			This driver supports a maximum of 8 queue pairs.
	The number of queue pairs used is the lesser of the maximum supported by the			The number of queue pairs used is the lesser of the maximum supported by the
	driver and the hypervisor, the number of CPUs present in the guest, and this			driver and the hypervisor, the number of CPUs present in the guest, and this
	tunable if not zero.			tunable if not zero.
	The default value is 0.			The default value is 0.
	.It Va hw.vtnet.tso_maxlen			.It Va hw.vtnet.tso_maxlen
	.It Va hw.vtnet. Ns Ar X Ns Va .tso_maxlen			.It Va hw.vtnet. Ns Ar X Ns Va .tso_maxlen
	This tunable sets the TSO burst limit.			This tunable sets the TSO burst limit.
	The default value is 65535.			The default value is 65535.
	.It Va hw.vtnet.rx_process_limit			.It Va hw.vtnet.rx_process_limit
	.It Va hw.vtnet. Ns Ar X Ns Va .rx_process_limit			.It Va hw.vtnet. Ns Ar X Ns Va .rx_process_limit
	This tunable sets the number of RX segments processed in one pass.			This tunable sets the number of RX segments processed in one pass.
	The default value is 1024.			The default value is 1024.
	.It Va hw.vtnet.lro_entry_count			.It Va hw.vtnet.lro_entry_count
	.It Va hw.vtnet. Ns Ar X Ns Va .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.			The default value is 128, the minimum value is 8.
	.It Va hw.vtnet.lro_mbufq_depth			.It Va hw.vtnet.lro_mbufq_depth
	.It Va hw.vtnet. Ns Ar X Ns Va .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.			The default value is 0.
	.It Va hw.vtnet.altq_disable			.It Va hw.vtnet.altq_disable
	This tunable disables ALTQ support, allowing the use of multiqueue instead.			This tunable disables ALTQ support, allowing the use of multiqueue instead.
	This option applies to all interfaces.			This option applies to all interfaces.
	The default value is 0.			The default value is 0.
	.El			.El
	.Sh TRANSMIT QUEUE STATISTICS			.Sh TRANSMIT QUEUE STATISTICS
	For each transmit queue of each interface the following read-only statistics			For each transmit queue of each interface the following read-only statistics
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