IRC channel logs

<damo22>it seems bpf doesnt seem to like ETH_P_ARP packets

<damo22>youpi: #define E1000_RCTL_BAM 0x00008000 /* broadcast enable */ this flag is set when ifup is set (i checked), so that means the NIC is configured to receive broadcast frames.

<damo22>if the nic accepts a broadcast frame, will that consume the frame or does it stay on the wire for other nics to accept?

<youpi>do you mean physically or in qemu?

<youpi>in principle it's sent to all nodes anyway

<youpi>normally virtualization networks don't diverge from that

<damo22>is a ping an ARP protocol frame?

<youpi>do you mean the icmp ping?

<youpi>icmp is on top of ip

<youpi>arp is directly on top of ethernet

<youpi>but for a ping, you need to know the mac address, so you need an arp first

<damo22>ok so i am sending an ARP but its getting lost

<damo22>using the ping command, it tries to first send an ARP i think

<youpi>sure

<damo22>i actually receive the same arp back

<youpi>that's not completely unexpected

<damo22>because its a broadcast destination

<youpi>notably since iirc you are using a capture to get the trafic, so you'll indeed see your own trafic

<youpi>(as tcpdump is expected to behave)

<damo22>but somehow i dont get a response arp from the host

<youpi>check whether it's the host that doesn't receive it, or gets it bogus, or doesn't answer, or the answer gets lost

<damo22>i tried setting SLIRP_DEBUG=call in my qemu invocation but i dont see any debug

<damo22>i am on libslirp0 4.4.0-1+deb11u2 on the host

<damo22>i used -debugcon /dev/pts/3

<damo22>(08:24:22 PM) youpi: check whether it's the host that doesn't receive it, or gets it bogus, or doesn't answer, or the answer gets lost

<damo22>i would like to, but i cant seem to figure out how to do that

<damo22>-net user,hostfwd=tcp::8888-:22 -net nic

<youpi>damo22: you probably need G_MESSAGES_DEBUG=all as well

<Pellescours>damo22: no, I didn’t

IRC channel logs

2025-06-06.log