Date: Wed, 8 Apr 2026 17:08:01 +0200 From: Miroslav Lachman <000.fbsd@quip.cz> To: net@freebsd.org Cc: ivy@freebsd.org Subject: Re: FreeBSD guest on Linux KVM, some vtnet(4) packets don't arrive Message-ID: <9ceaf2c2-26cd-430f-90ee-5f820d80a8cd@quip.cz> In-Reply-To: <adZocDxDXSBFXQGA@amaryllis.le-fay.org>
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On 08/04/2026 16:38, Lexi Winter wrote: > hello, > > i'm using FreeBSD main: > > FreeBSD 16.0-CURRENT #0 main-n284768-e6eba5076929: Mon Mar 30 16:07:28 UTC 2026 > root@releng3.nyi.freebsd.org:/usr/obj/usr/src/powerpc.powerpc64/sys/GENERIC64 [..] > vtnet0: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500 > options=cc00ba<TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,VLAN_HWTSO,LINKSTATE,TXCSUM_IPV6,HWSTATS> > ether 52:54:00:12:34:56 > inet6 fe80::2%vtnet0 prefixlen 64 scopeid 0x1 > media: Ethernet autoselect (10Gbase-T <full-duplex>) > status: active > nd6 options=821<PERFORMNUD,AUTO_LINKLOCAL,STABLEADDR> > 15:34:39.106898 IP6 fd00:0:0:1::12 > fd00:0:0:1::b: ICMP6, echo request, id 49664, seq 3, length 64 > 15:34:40.106951 IP6 fd00:0:0:1::12 > fd00:0:0:1::b: ICMP6, echo request, id 49664, seq 4, length 64 > > but these packets never arrive on the guest; tcpdump shows nothing. > > however, 'netstat -in' shows that the packets *are* arriving on the guest, > since Ipkts increments for each ICMP packet. it seems like they're just > getting lost somewhere in the network stack. (Ierrs/Oerrs is zero.) > > does anyone have any ideas what might be causing this? Can you try disabling rxcsum / txcsum? (add -rxcsum -txcsum to ifconfig_vtnet0 in rc.conf) I had similar problem in the past on KVM hosted FreeBSD guest and this solved the problem for me. Kind regards Miroslav Lachmanhome | help
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