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Date:      Wed, 2 Aug 2017 05:00:19 +0200
From:      John Keates <>
Subject:   FreeBSD 11.0 (pfSense 2.4) kernel panic with more than 3 Xen (4.8.1) VIF's
Message-ID:  <>

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I=E2=80=99m using FreeBSD 11.0 (technically in a pfSense 2.4 =
distribution form) in a VM (HVM with PV on for optimised virtual =
devices) using Xen 4.8.1. (management OS is Debian Stretch).
When starting the VM with 3 or less network interfaces, everything works =
fine, but as soon as I add a 4th interface the VM gets a kernel panic =
and dumps (and reboots). When adding a 5th or more interface and booting =
it doesn=E2=80=99t even dump anymore, it panics and immediately goes =
into db>.

Configuration file for the VM:

name =3D 'firewall'
bios =3D "ovmf"
builder =3D 'hvm'
memory =3D '2024'
vcpus =3D 4
disk =3D ['file:/dev/hypervisor-local/firewall-system,xvda,w']
vif =3D [
'mac=3D00:16:3e:e5:68:fd, bridge=3Dwan0, =
script=3Dvif-openvswitch-no-offload, type=3Dvif',
'mac=3D00:16:3e:e8:20:db, bridge=3Dlan10, =
script=3Dvif-openvswitch-no-offload, type=3Dvif',
#'mac=3D00:16:3e:ee:02:44, bridge=3Dlan20, =
script=3Dvif-openvswitch-no-offload, type=3Dvif',
#'mac=3D00:16:3e:e1:03:f1, bridge=3Dlan30, =
script=3Dvif-openvswitch-no-offload, type=3Dvif',
'mac=3D00:16:3e:e2:30:44, bridge=3Dlan40, =
script=3Dvif-openvswitch-no-offload, type=3Dvif'
boot =3D 'c'

Disk image used for installation: =
mstick-serial-2.4.0-BETA-amd64-latest.img.gz =
emstick-serial-2.4.0-BETA-amd64-latest.img.gz> (added as xvdb)

Initial panic lines (with 4 interfaces):

panic: HYPERVISOR_memory_op failed to map gnttab
cpuid =3D 2
KDB: enter: panic
[ thread pid 26 tid 100093 ]
Stopped at      kdb_enter+0x3b: movq    $0,kdb_why

Mostly complete crash dump: =
I can supply the dumps themselves as well I suppose, they should still =
be stored on the system. If needed I should be able to re-create this on =
pure FreeBSD 11.0 too.

Has this type of problem with the netback/netfront combination with =
FreeBSD and Xen been happening before? And if so, was it resolved? I =
couldn=E2=80=99t find anything matching my case, but I might not be =
using the right search options.


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