Hi, I am observing an interesting phenomenon on the latest QEMU git and the latest HelenOS mainline (the problem is likely guest-neutral though). The QEMU command line is as follows:
$ qemu-system-i386 -device rtl8139,vlan=0 -net user -boot d -redir \ udp:8080::8080 -redir udp:8081::8081 -redir tcp:8080::8080 -redir \ tcp:8081::8081 -cdrom image.iso Now after I configure networking in HelenOS and start listening on the 8080 UDP port, I do this on the host as the first networking activity: $ echo foo | nc -u 127.0.0.1 8080 What I observe inside HelenOS is an ARP request from 10.0.2.2. After HelenOS replies, there is no more network traffic, i.e. the UDP datagram is not retransmitted. But when repeat the nc command for the second time, the datagram gets normally through without any additional ARP requests. This makes me think that QEMU for some reason does not attempt to retransmit the UDP packet after it learns the MAC address of 10.0.2.15. I collected QEMU networking trace, the relevant part seems to be this: if_start... if_start... if_start... if_start... sorecvfrom... so = 232db0a8 m_get... m = 2334a808 did recvfrom 4, errno = 11-Resource temporarily unavailable udp_output... so = 232db0a8 m = 2334a808 saddr = 202000a daddr = f02000a ip_output... so = 232db0a8 m0 = 2334a808 if_output... so = 232db0a8 ifm = 2334a808 if_start... arp_table_search... ip = 0xf02000a [1295 more instances of arp_table_search] if_start... arp_table_search... ip = 0xf02000a if_start... m_free... m = 2334a808 if_start... if_start... if_start... if_start... if_start... if_start... if_start... if_start... if_start... if_start... if_start... if_start... if_start... if_start... ip_slowtimo... tcp_slowtimo... if_start... if_start... [end of emulation] [slirp cleanup] There is a HelenOS ticket for this also: http://trac.helenos.org/ticket/442 Is this a known SLIRP issue or am I missing something important here? Jakub
