RADPx-OS Crimson 0.1.4 includes an experimental networking path for the x86 VM target. The goal of this surface is to prove the kernel interfaces for network devices, packet receive, POSIX-inspired datagram sockets, host-verified UDP, SNTP/NTP sampling, and the first TCP stream socket lifecycle before adding a complete wire-level TCP/IP stack or target-specific production drivers.

Current Stack

The network device API exposes link information, frame transmit, frame receive, and polling. The x86 VM target registers a legacy virtio-net device as /dev/net0 when QEMU exposes one. The VM backend now programs separate legacy virtio RX and TX rings and emits smoke markers when the rings are owned by the guest.

The minimal IPv4 path now includes Ethernet II dispatch, ARP request/reply and cache learning, IPv4 checksum validation, UDP transmit/receive, ICMP echo reply, static default-gateway routing, IPv4 DNS A-record lookup, and SNTP/NTP sampling. RADPx-OS uses this path for host UDP echo verification and can query either the deterministic host-side test responder or public NTP servers.

The socket layer currently supports:

RAD_AF_INET
RAD_SOCK_DGRAM
RAD_IPPROTO_UDP
socket, bind, sendto, recvfrom
getaddrinfo, freeaddrinfo, gethostbyname
inet_aton, inet_pton(AF_INET), inet_ntop(AF_INET)
RAD_SOCK_STREAM
RAD_IPPROTO_TCP
listen, accept, connect, send, recv, shutdown
fd lifecycle through close, dup, dup2, fcntl, fork inheritance, and close-on-exec handling

The x86 sysroot also exposes minimal sys/socket.h, netinet/in.h, and arpa/inet.h headers plus libc wrappers for the socket calls above.

The TCP support in this pass is a kernel socket model and local stream foundation. It verifies listener setup, client connect, accept, connected peer state, stream byte delivery, and shutdown behavior. It is not yet a full wire-level TCP implementation with SYN/ACK sequencing, retransmit timers, congestion control, route lookup, or external host connections.

The default VM IPv4 profile is static and QEMU-oriented:

guest: 10.0.2.15
netmask: 255.255.255.0
gateway/host side: 10.0.2.2
default DNS resolver: 10.0.2.3
default SNTP/NTP target: time.google.com:123
MTU: 1500

RADBuild/rkconfig can override these with network_enabled, net_ipv4, net_netmask, net_gateway, net_ntp_server, net_ntp_port, and net_dns_server. Deterministic VM smoke runs may still override NTP to 10.0.2.2:12300 and use the host UDP/NTP responder.

The rash shell includes:

net to show /dev/net0, static IPv4 state, counters, ARP cache count, and default NTP target
ntpdate [-q] [host-or-ip] [port] to run a userspace UDP SNTP/NTP query, resolve hostnames through DNS, and set the realtime clock unless -q is used

Current Limits

This page is intentionally marked experimental. UDP datagrams, local TCP stream sockets, virtio-net queue setup, host UDP echo, and NTP sampling are verified through x86 VM smoke markers, but the network stack is still minimal. DHCP, IPv6, DNS caching, TCP DNS fallback, full wire-level TCP, richer route tables, firewall rules, packet sockets, and non-x86 NIC drivers remain future work.

Verification

Host tests cover network device registration, link info, transmit, receive, UDP datagram socket delivery, and the local TCP listener/connect/accept/stream socket lifecycle.

The x86 Slint VM smoke gate checks:

RAD_VIRTIO_NET_FOUND
RAD_NET_DEVICE_REGISTERED
RAD_VIRTIO_NET_TX_RING_OK
RAD_VIRTIO_NET_RX_RING_OK
RAD_ETH_TX_OK
RAD_ARP_OK
RAD_IPV4_OK
RAD_UDP_OK
RAD_UDP_RX_OK
RAD_NET_UDP_TX_OK
RAD_NET_UDP_RX_OK
RAD_NET_HOST_UDP_ECHO_OK
RAD_NTP_QUERY_OK
RAD_NTP_RESPONSE_OK
RAD_NTP_TIME_SAMPLE_OK
RAD_SOCKET_DGRAM_OK
RAD_TCP_SOCKET_OK
RAD_TCP_CONNECT_OK
RAD_TCP_LISTEN_ACCEPT_OK
RAD_TCP_STREAM_IO_OK
RAD_TCP_SHUTDOWN_OK