Virtual Network Card (VNIC)

Device Type: 0x29FEF534
CLI Name: Vnic
Event Interrupt: 0x73 (NicNotification)

The virtual network card is a command-based serial device that sends and receives Ethernet-like frames over UDP.

Descriptor layout

Each TX/RX ring entry is 9 bytes:

Offset	Size	Meaning
0	4	Guest buffer address
4	4	Buffer length in bytes
8	1	Descriptor flags

Descriptor flags

Flag	Value	Meaning
Own	0x01	Descriptor is owned by the device
EndOfPacket	0x02	Last descriptor for a packet
Done	0x04	Device finished processing descriptor

Status flags (GetStatus)

Flag	Value	Meaning
ReceiveDone	0x01	One or more frames were received
TransmitDone	0x02	One or more frames were transmitted
PacketDropped	0x04	RX ring had no available descriptor
LinkUp	0x08	Link is up
TransmitError	0x10	One or more TX operations failed

GetStatus returns current flags, then clears all flags except LinkUp.

Commands

Command	ID	Args
Reset	1	none
Set MAC	2	2
Set TX ring	3	2
Set RX ring	4	2
Kick TX	5	none
Get status	6	none

Reset

Clears MAC address, ring configuration, and internal state.

Set MAC

Sets the local MAC address used for incoming unicast filtering.

Arguments are packed little-endian:

• arg0: bytes 0..3
• arg1: bytes 4..5

Set TX ring

Arguments:

1. ring base address
2. descriptor count

Set RX ring

Arguments:

1. ring base address
2. descriptor count

Kick TX

Scans the TX ring and sends descriptors with Own set.

Get status

Enqueues one status value for in to read.

RX filtering behavior

Incoming frames are accepted when:

• frame length is at least 14 bytes
• destination MAC is broadcast (FF:FF:FF:FF:FF:FF) or matches the configured MAC

Otherwise the frame is dropped.