Hi Stefano,
Thanks!
I used xen-guest-image-minimal(simple console based image) as a guest with
fbcon & fbdev enabled in kernel configurations but still the same error
can't open the display.
below are the outcome of "xenstore-ls":
*root@raspberrypi4-64:~/guest1# xenstore-lstool = "" xenstored = ""local =
"" domain = "" 0 = "" control = "" feature-poweroff = "1"
feature-reboot = "1" domid = "0" name = "Domain-0" device-model = ""
0 = "" backends = "" console = "" vkbd = "" vfb = ""
qnic = "" state = "running" 1 = "" backends = ""
console = "" vkbd = "" vfb = "" qnic = "" state =
"running" backend = "" vbd = "" 1 = "" 51712 = ""
frontend = "/local/domain/1/device/vbd/51712" params =
"/home/root/guest2/xen-guest-image-minimal-raspberrypi4-64.ext3"
script = "/etc/xen/scripts/block" frontend-id = "1" online =
"1" removable = "0" bootable = "1" state = "4" dev
= "xvda" type = "phy" mode = "w" device-type = "disk"
discard-enable = "1" feature-max-indirect-segments = "256"
multi-queue-max-queues = "4" max-ring-page-order = "4" node =
"/dev/loop0" physical-device = "7:0" physical-device-path =
"/dev/loop0" hotplug-status = "connected" feature-flush-cache =
"1" discard-granularity = "4096" discard-alignment = "0"
discard-secure = "0" feature-discard = "1" feature-barrier =
"1" feature-persistent = "1" sectors = "1794048" info =
"0" sector-size = "512" physical-sector-size = "512" vfb =
"" 1 = "" 0 = "" frontend = "/local/domain/1/device/vfb/0"
frontend-id = "1" online = "1" state = "4" vnc =
"1" vnclisten = "127.0.0.1" vncdisplay = "0" vncunused =
"1" sdl = "0" opengl = "0" feature-resize = "1"
hotplug-status = "connected" request-update = "1" vkbd = "" 1
= "" 0 = "" frontend = "/local/domain/1/device/vkbd/0"
frontend-id = "1" online = "1" state = "4"
feature-abs-pointer = "1" feature-raw-pointer = "1"
hotplug-status = "connected" console = "" 1 = "" 0 = ""
frontend = "/local/domain/1/console" frontend-id = "1" online
= "1" state = "1" protocol = "vt100" vif = "" 1 = ""
0 = "" frontend = "/local/domain/1/device/vif/0" frontend-id
= "1" online = "1" state = "4" script =
"/etc/xen/scripts/vif-bridge" mac = "e4:5f:01:cd:7b:dd" bridge
= "xenbr0" handle = "0" type = "vif" hotplug-status =
"connected" feature-sg = "1" feature-gso-tcpv4 = "1"
feature-gso-tcpv6 = "1" feature-ipv6-csum-offload = "1"
feature-rx-copy = "1" feature-xdp-headroom = "1"
feature-rx-flip = "0" feature-multicast-control = "1"
feature-dynamic-multicast-control = "1" feature-split-event-channels
= "1" multi-queue-max-queues = "4" feature-ctrl-ring = "1" 1 =
"" vm = "/vm/d81ec5a9-5bf9-4f2b-89e8-0f60d6da948f" name = "guest2"
cpu = "" 0 = "" availability = "online" 1 = "" availability
= "online" memory = "" static-max = "2097152" target = "2097152"
videoram = "0" device = "" suspend = "" event-channel = "" vbd
= "" 51712 = "" backend = "/local/domain/0/backend/vbd/1/51712"
backend-id = "0" state = "4" virtual-device = "51712"
device-type = "disk" multi-queue-num-queues = "2" queue-0 = ""
ring-ref = "8" event-channel = "4" queue-1 = ""
ring-ref = "9" event-channel = "5" protocol = "arm-abi"
feature-persistent = "1" vfb = "" 0 = "" backend =
"/local/domain/0/backend/vfb/1/0" backend-id = "0" state = "4"
page-ref = "275022" event-channel = "3" protocol = "arm-abi"
feature-update = "1" vkbd = "" 0 = "" backend =
"/local/domain/0/backend/vkbd/1/0" backend-id = "0" state = "4"
request-abs-pointer = "1" page-ref = "275322" page-gref =
"1284" event-channel = "10" vif = "" 0 = "" backend =
"/local/domain/0/backend/vif/1/0" backend-id = "0" state = "4"
handle = "0" mac = "e4:5f:01:cd:7b:dd" mtu = "1500"
xdp-headroom = "0" multi-queue-num-queues = "2" queue-0 = ""
tx-ring-ref = "1280" rx-ring-ref = "1281" event-channel-tx =
"6" event-channel-rx = "7" queue-1 = "" tx-ring-ref =
"1282" rx-ring-ref = "1283" event-channel-tx = "8"
event-channel-rx = "9" request-rx-copy = "1" feature-rx-notify =
"1" feature-sg = "1" feature-gso-tcpv4 = "1"
feature-gso-tcpv6 = "1" feature-ipv6-csum-offload = "1" control =
"" shutdown = "" feature-poweroff = "1" feature-reboot = "1"
feature-suspend = "" sysrq = ""
platform-feature-multiprocessor-suspend = "1"
platform-feature-xs_reset_watches = "1" data = "" drivers = ""
feature = "" attr = "" error = "" domid = "1" store = "" port =
"1" ring-ref = "233473" console = "" backend =
"/local/domain/0/backend/console/1/0" backend-id = "0" limit =
"1048576" type = "xenconsoled" output = "pty" tty = "/dev/pts/1"
port = "2" ring-ref = "233472" vnc-listen = "127.0.0.1" vnc-port
= "5900" image = "" device-model-pid = "788"vm =
"" d81ec5a9-5bf9-4f2b-89e8-0f60d6da948f = "" name = "guest2" uuid =
"d81ec5a9-5bf9-4f2b-89e8-0f60d6da948f" start_time = "1520600274.27"libxl =
"" 1 = "" device = "" vbd = "" 51712 = "" frontend =
"/local/domain/1/device/vbd/51712" backend =
"/local/domain/0/backend/vbd/1/51712" params =
"/home/root/guest2/xen-guest-image-minimal-raspberrypi4-64.ext3" script
= "/etc/xen/scripts/block" frontend-id = "1" online = "1"
removable = "0" bootable = "1" state = "1" dev = "xvda"
type = "phy" mode = "w" device-type = "disk" discard-enable =
"1" vfb = "" 0 = "" frontend = "/local/domain/1/device/vfb/0"
backend = "/local/domain/0/backend/vfb/1/0" frontend-id = "1"
online = "1" state = "1" vnc = "1" vnclisten = "127.0.0.1"
vncdisplay = "0" vncunused = "1" sdl = "0" opengl = "0" vkbd
= "" 0 = "" frontend = "/local/domain/1/device/vkbd/0" backend =
"/local/domain/0/backend/vkbd/1/0" frontend-id = "1" online = "1"
state = "1" console = "" 0 = "" frontend =
"/local/domain/1/console" backend =
"/local/domain/0/backend/console/1/0" frontend-id = "1" online =
"1" state = "1" protocol = "vt100" vif = "" 0 = ""
frontend = "/local/domain/1/device/vif/0" backend =
"/local/domain/0/backend/vif/1/0" frontend-id = "1" online = "1"
state = "1" script = "/etc/xen/scripts/vif-bridge" mac =
"e4:5f:01:cd:7b:dd" bridge = "xenbr0" handle = "0" type =
"vif" hotplug-status = "" type = "pvh" dm-version =
"qemu_xen"root@raspberrypi4-64:~/guest1#*
Any input as per above? Looking forward to hearing from you.
Regards,
Vipul Kumar
On Wed, Oct 26, 2022 at 5:21 AM Stefano Stabellini <[email protected]>
wrote:
> Hi Vipul,
>
> If you look at the QEMU logs, it says:
>
> VNC server running on 127.0.0.1:5900
>
> That is the VNC server you need to connect to. So in theory:
>
> vncviewer 127.0.0.1:5900
>
> should work correctly.
>
>
> If you have:
>
> vfb = ["type=vnc"]
>
> in your xl config file and you have "fbdev" in your Linux guest, it
> should work.
>
> If you connect to the VNC server but you get a black screen, it might be
> a guest configuration issue. I would try with a simpler guest, text only
> (no X11, no Wayland) and enable the fbdev console (fbcon). See
> Documentation/fb/fbcon.rst in Linux. You should be able to see a
> graphical console over VNC.
>
> If that works, then you know that the fbdev kernel driver (xen-fbfront)
> works correctly.
>
> If it doesn't work, the output of "xenstore-ls" would be interesting.
>
> Cheers,
>
> Stefano
>
>
> On Wed, 19 Oct 2022, Vipul Suneja wrote:
> > Hi Stefano,
> >
> > Thanks for the response!
> >
> > I am following the same link you shared from the beginning. Tried the
> command "vncviewer localhost:0" in DOM0 but same issue "Can't open
> > display", below are the logs:
> >
> > root@raspberrypi4-64:~# vncviewer localhost:0
> >
> > TigerVNC Viewer 64-bit v1.11.0
> > Built on: 2020-09-08 12:16
> > Copyright (C) 1999-2020 TigerVNC Team and many others (see README.rst)
> > See https://www.tigervnc.org for information on TigerVNC.
> > Can't open display:
> >
> > Below are the netstat logs, i couldn't see anything running at port 5900
> or 5901:
> >
> > root@raspberrypi4-64:~# netstat -tuwx
> > Active Internet connections (w/o servers)
> > Proto Recv-Q Send-Q Local Address Foreign Address
> State
> > tcp 0 164 192.168.1.39:ssh 192.168.1.38:37472
> ESTABLISHED
> > Active UNIX domain sockets (w/o servers)
> > Proto RefCnt Flags Type State I-Node Path
> > unix 8 [ ] DGRAM CONNECTED 10565 /dev/log
> > unix 3 [ ] STREAM CONNECTED 10891
> /var/run/xenstored/socket
> > unix 3 [ ] STREAM CONNECTED 13791
> > unix 3 [ ] STREAM CONNECTED 10843
> /var/run/xenstored/socket
> > unix 3 [ ] STREAM CONNECTED 10573
> /var/run/xenstored/socket
> > unix 2 [ ] DGRAM CONNECTED 14510
> > unix 3 [ ] STREAM CONNECTED 13249
> > unix 2 [ ] DGRAM CONNECTED 13887
> > unix 2 [ ] DGRAM CONNECTED 10599
> > unix 3 [ ] STREAM CONNECTED 14005
> > unix 3 [ ] STREAM CONNECTED 13258
> > unix 3 [ ] STREAM CONNECTED 13248
> > unix 3 [ ] STREAM CONNECTED 14003
> > unix 3 [ ] STREAM CONNECTED 10572
> /var/run/xenstored/socket
> > unix 3 [ ] STREAM CONNECTED 10786
> /var/run/xenstored/socket
> > unix 3 [ ] DGRAM CONNECTED 13186
> > unix 3 [ ] STREAM CONNECTED 10864
> /var/run/xenstored/socket
> > unix 3 [ ] STREAM CONNECTED 10812
> /var/run/xenstored/socket
> > unix 2 [ ] DGRAM CONNECTED 14083
> > unix 3 [ ] STREAM CONNECTED 10813
> /var/run/xenstored/socket
> > unix 3 [ ] STREAM CONNECTED 14068
> > unix 3 [ ] STREAM CONNECTED 13256
> > unix 3 [ ] STREAM CONNECTED 10571
> /var/run/xenstored/socket
> > unix 3 [ ] STREAM CONNECTED 10842
> > unix 3 [ ] STREAM CONNECTED 13985
> > unix 3 [ ] DGRAM CONNECTED 13185
> > unix 2 [ ] STREAM CONNECTED 13884
> > unix 2 [ ] DGRAM CONNECTED 14528
> > unix 2 [ ] DGRAM CONNECTED 13785
> > unix 3 [ ] STREAM CONNECTED 14034
> >
> > Attaching xen log files of /var/log/xen.
> > I didn't get the role of QEMU here because as mentioned earlier, I am
> porting in raspberrypi 4B.
> >
> > Regards,
> > Vipul Kumar
> >
> > On Wed, Oct 19, 2022 at 12:43 AM Stefano Stabellini <
> [email protected]> wrote:
> > It usually works the way it is described in the guide:
> >
> >
> https://www.virtuatopia.com/index.php?title=Configuring_a_VNC_based_Graphical_Console_for_a_Xen_Paravirtualized_domainU_Guest
> >
> > You don't need to install any VNC-related server software because
> it is
> > already provided by Xen (to be precise it is provided by QEMU
> working
> > together with Xen.)
> >
> > You only need the vnc client in dom0 so that you can connect, but
> you
> > could also run the vnc client outside from another host. So
> basically
> > the following should work when executed in Dom0 after creating
> DomU:
> >
> > vncviewer localhost:0
> >
> > Can you attach the Xen and QEMU logs (/var/log/xen/*)? And also use
> > netstat -taunp to check if there is anything running at port 5900
> or
> > 5901?
> >
> > Cheers,
> >
> > Stefano
> >
> >
> > On Tue, 18 Oct 2022, Vipul Suneja wrote:
> > > Hi Stefano,
> > >
> > > Thanks for the response!
> > >
> > > I could install tigerVNC, x11vnc & libvncserver in Dom0
> xen-image-minimal but only manage to install libvncserver(couldn't
> > install tigervnc
> > > & x11vnc because of x11
> > > support missing, it's wayland) in DOMU custom graphical image. I
> tried running vncviewer with IP address & port in dom0 to
> > access the domu
> > > graphical image display as per below commands.
> > >
> > > vncviewer 192.168.1.42:5901
> > >
> > > But it showing can't open display, below are the logs:
> > >
> > > root@raspberrypi4-64:~/guest1# vncviewer 192.168.1.42:5901
> > >
> > > TigerVNC Viewer 64-bit v1.11.0
> > > Built on: 2020-09-08 12:16
> > > Copyright (C) 1999-2020 TigerVNC Team and many others (see
> README.rst)
> > > See https://www.tigervnc.org for information on TigerVNC.
> > > Can't open display:
> > > root@raspberrypi4-64:~/guest1#
> > >
> > > I am not exactly sure what the issue is but I thought only
> libvncserver in DOMU could work to get access but it did not
> > work.
> > > If TigerVNC is the issue here then is there any other VNC source
> which could be installed for both x11 & wayland supported
> > images?
> > >
> > > Regards,
> > > Vipul Kumar
> > >
> > > On Tue, Oct 18, 2022 at 2:40 AM Stefano Stabellini <
> [email protected]> wrote:
> > > VNC is typically easier to setup, because SDL needs extra
> libraries at
> > > build time and runtime. If QEMU is built without SDL
> support it won't
> > > start when you ask for SDL.
> > >
> > > VNC should work with both x11 and wayland in your domU. It
> doesn't work
> > > at the x11 level, it exposes a special fbdev device in
> your domU that
> > > should work with:
> > > - a graphical console in Linux domU
> > > - x11
> > > - wayland (but I haven't tested this so I am not 100% sure
> about it)
> > >
> > > When you say "it doesn't work", what do you mean? Do you
> get a black
> > > window?
> > >
> > > You need CONFIG_XEN_FBDEV_FRONTEND in Linux domU
> > > (drivers/video/fbdev/xen-fbfront.c). I would try to get a
> graphical text
> > > console up and running in your domU before attempting
> x11/wayland.
> > >
> > > Cheers,
> > >
> > > Stefano
> > >
> > > On Mon, 17 Oct 2022, Vipul Suneja wrote:
> > > > Hi,
> > > > Thanks!
> > > >
> > > > I have ported xen minimal image as DOM0 & custom wayland
> GUI based image as DOMU in raspberry pi4B. I am trying to
> > make GUI
> > > display up
> > > > for guest machine. I tried using sdl, included below
> line in guest.conf file
> > > > vfb= [ 'sdl=1' ]
> > > >
> > > > But it is throwing below error:
> > > >
> > > > root@raspberrypi4-64:~/guest1# xl create -c guest1.cfg
> > > > Parsing config from guest1.cfg
> > > > libxl: error: libxl_qmp.c:1400:qmp_ev_fd_callback:
> Domain 3:error on QMP socket: Connection reset by peer
> > > > libxl: error: libxl_qmp.c:1439:qmp_ev_fd_callback:
> Domain 3:Error happened with the QMP connection to QEMU
> > > > libxl: error:
> libxl_dm.c:3351:device_model_postconfig_done: Domain 3:Post DM startup
> configs failed, rc=-26
> > > > libxl: error:
> libxl_create.c:1867:domcreate_devmodel_started: Domain 3:device model did
> not start: -26
> > > > libxl: error: libxl_aoutils.c:646:libxl__kill_xs_path:
> Device Model already exited
> > > > libxl: error: libxl_domain.c:1183:libxl__destroy_domid:
> Domain 3:Non-existant domain
> > > > libxl: error:
> libxl_domain.c:1137:domain_destroy_callback: Domain 3:Unable to destroy
> guest
> > > > libxl: error: libxl_domain.c:1064:domain_destroy_cb:
> Domain 3:Destruction of domain failed
> > > >
> > > > Another way is VNC, i could install tigervnc in DOM0 but
> same i couldn't in guest machine because it doesn't support
> > > x11(supports wayland
> > > > only). I am completely blocked here, Need your support
> to enable the display up.
> > > > Any alternative of VNC which could work in both x11 &
> wayland supported images?
> > > >
> > > > Any input on VNC, SDL or any other way to proceed on
> this? Looking forward to hearing from you.
> > > >
> > > > Regards,
> > > > Vipul Kumar
> > >
> > >
> > >
> >
> >
> >
