HVM DomU RouterOS CHR Hangs When Rebooting

[Konstantin <konstantin@xxxxxxxx>]

Hi guys,

I've recently installed a Mikrotik CHR RouterOS as HVM domU guest 
machine and it is working fine except for one thing. Every time I 
initiate reboot procedure in domU it hangs without any error and is not 
coming up until I destroy it with "xl destroy" and recreate it with "xl 
create" again. Shutting down this domU guest works as expected.
I tried to contact this OS vendor Mikrotik but their answer was that Xen 
isn't officially supported and I should move for another hypervisor 
platform. I'm wondering if there is any known quirk to fix the reboot 
issue with this HVM domU to avoid such migration.
Below is the configuration of my domU HVM guest machine which I believe 
is quite simple.
----------------------------------------------------------------------------------------------------------------
hostname ~ # xl info
host                   : hostname
release                : 5.15.52-gentoo-dom0-x86_64
version                : #1 SMP Tue Jul 12 04:25:10 UTC 2022
machine                : x86_64
nr_cpus                : 16
max_cpu_id             : 15
nr_nodes               : 1
cores_per_socket       : 8
threads_per_core       : 2
cpu_mhz                : 2099.998
hw_caps                : 
bfebfbff:77fef3ff:2c100800:00000121:00000001:021cbfbb:00000000:00000100
virt_caps              : pv hvm hvm_directio pv_directio hap shadow 
iommu_hap_pt_share
total_memory           : 130969
free_memory            : 54782
sharing_freed_memory   : 0
sharing_used_memory    : 0
outstanding_claims     : 0
free_cpus              : 0
xen_major              : 4
xen_minor              : 15
xen_extra              : .3
xen_version            : 4.15.3
xen_caps               : xen-3.0-x86_64 hvm-3.0-x86_32 hvm-3.0-x86_32p 
hvm-3.0-x86_64
xen_scheduler          : credit2
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          :
xen_commandline        : placeholder dom0_mem=16384M,max:16384M 
dom0_max_vcpus=8 dom0_vcpus_pin no-real-mode edd=off
cc_compiler            : gcc (Gentoo 11.3.0 p4) 11.3.0
cc_compile_by          :
cc_compile_domain      :
cc_compile_date        : Mon Jul 11 22:55:40 UTC 2022
build_id               : 79d66d0f872f7848c9bf484057503d40955f0b03
xend_config_format     : 4
----------------------------------------------------------------------------------------------------------------

hostname ~ # xl create chr-test.cfg -d
Parsing config from chr-test.cfg
{
    "c_info": {
        "type": "hvm",
        "name": "chr-test",
        "uuid": "95437cd5-3a94-4523-853f-fd8b509cd213",
        "run_hotplug_scripts": "True"
    },
    "b_info": {
        "max_vcpus": 1,
        "avail_vcpus": [
            0
        ],
        "max_memkb": 1048576,
        "target_memkb": 1048576,
        "localtime": "False",
        "sched_params": {

        },
        "claim_mode": "True",
        "type.hvm": {
            "vga": {

            },
            "vnc": {
                "enable": "True",
                "passwd": "password"
            },
            "sdl": {

            },
            "spice": {

            },
            "serial": "pty",
            "boot": "c",
            "rdm": {

            }
        },
        "arch_arm": {

        },
        "arch_x86": {

        }
    },
    "disks": [
        {
            "pdev_path": "/dev/zvol/zpool/chr/sda",
            "vdev": "sda",
            "format": "raw",
            "readwrite": 1
        }
    ],
    "nics": [
        {
            "devid": 0,
            "mac": "00:16:3e:12:34:56",
            "bridge": "xenbr0:11:19",
            "script": "vif-openvswitch"
        },
        {
            "devid": 1,
            "mac": "00:16:3e:12.34.57",
            "bridge": "xenbr0.2",
            "script": "vif-openvswitch"
        }
    ],
    "on_reboot": "restart",
    "on_soft_reset": "soft_reset"
}

----------------------------------------------------------------------------------------------------------------


--
BR,
Konstantin