FreeBSD 11.0 (pfSense 2.4) kernel panic with more than 3 Xen (4.8.1) VIF's

[John Keates]

Hi,

I’m 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’t even dump anymore, it panics and immediately goes into db>.

Configuration file for the VM:

name = 'firewall'
bios = "ovmf"
uuid="11d1366c-40e2-43b2-83be-52cfe0c6542d"
builder = 'hvm'
memory = '2024'
vcpus = 4
disk = ['file:/dev/hypervisor-local/firewall-system,xvda,w']
vif = [
'mac=00:16:3e:e5:68:fd, bridge=wan0, script=vif-openvswitch-no-offload, type=vif',
'mac=00:16:3e:e8:20:db, bridge=lan10, script=vif-openvswitch-no-offload, type=vif',
#'mac=00:16:3e:ee:02:44, bridge=lan20, script=vif-openvswitch-no-offload, type=vif',
#'mac=00:16:3e:e1:03:f1, bridge=lan30, script=vif-openvswitch-no-offload, type=vif',
'mac=00:16:3e:e2:30:44, bridge=lan40, script=vif-openvswitch-no-offload, type=vif'
]
boot = 'c'
serial=‘pty'

Disk image used for installation: https://snapshots.pfsense.org/amd64/pfSense_master/installer/pfSense-CE-memstick-serial-2.4.0-BETA-amd64-latest.img.gz <https://snapshots.pfsense.org/amd64/pfSense_master/installer/pfSense-CE-memstick-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 = 2
KDB: enter: panic
[ thread pid 26 tid 100093 ]
Stopped at      kdb_enter+0x3b: movq    $0,kdb_why

Mostly complete crash dump: https://forum.pfsense.org/index.php?topic=134533.0
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’t find anything matching my case, but I might not be using the right search options.

Regards,
John