Xen networking problems in -current with xn driver?

[Roger Pau Monné]

On Wed, Aug 03, 2016 at 02:12:33AM +0800, Julian Elischer wrote:
> I upgraded my VPS machine to today's current, and on reboot I couldn't get
> into it by network.
> 
> A quick switch to the VNC console showed that it was up but that it couldn't
> get out.
> 
> 
> The xn interfaces said they were UP but attempts to get out were met with
> "network is down".
> 
> if I did 'tcpdump -n -i xn0' (and xn1) hten all was fine again.
> 
> tcpdump saw packets, and in fact ipfw saw some packets coming in even before
> that but it was not possible to send.
> 
> 
> Has anyone seen similar?

Hello,

I've tested current less than one week ago and didn't find any issues, I'm 
currently updating to see if it's something that has been introduced in the 
last few days. There have also been reports of it working fine on the
freebsd-xen mailing list, but I guess there's something different with your 
setup:

https://lists.freebsd.org/pipermail/freebsd-xen/2016-July/002779.html

> some relevant parts of the dmesg output.:
> 
> 
> T(vga): text 80x25
> XEN: Hypervisor version 3.4 detected.
> CPU: Intel(R) Xeon(R) CPU           E5620  @ 2.40GHz (2400.05-MHz 686-class
> CPU)
>   Origin="GenuineIntel"  Id=0x206c2  Family=0x6  Model=0x2c Stepping=2
> Features=0x1781fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,MMX,FXSR,SSE,SSE2,HTT>
> Features2=0x80982201<SSE3,SSSE3,CX16,SSE4.1,SSE4.2,POPCNT,HV>
>   AMD Features=0x20100000<NX,LM>
>   AMD Features2=0x1<LAHF>
> Hypervisor: Origin = "XenVMMXenVMM"
> real memory  = 536870912 (512 MB)
> avail memory = 503783424 (480 MB)
> Event timer "LAPIC" quality 400
> ACPI APIC Table: <Xen HVM>
> WARNING: L1 data cache covers less APIC IDs than a core
> 0 < 1
> WARNING: L2 data cache covers less APIC IDs than a core
> 0 < 1
> WARNING: L3 data cache covers less APIC IDs than a core
> 0 < 1
> 
> ipfw2 (+ipv6) initialized, divert loadable, nat enabled, default to deny,

You seem to be using ipfw, I guess you have firewall_enable="YES" on you 
rc.conf, are you also using IPv6? Anything else net related on your rc.conf?

Roger.