Xen project Mailing List

On Fri, Nov 11, 2022 at 6:40 AM Stefano Stabellini <sstabellini@xxxxxxxxxx> wrote:

Hi Vipul,

Sorry for the late reply. From the earlier logs that you sent, it looks
like everything should be working correctly. Specifically:

   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"

state "4" means "connected". So I would expect that you should be able
to connect to the vnc server using vncviewer. You might not see anything
(black screen) but you should definitely be able to connect.

I wouldn't try to launch x11 in the guest just yet. fbcon in Linux is
enough to render something on the screen. You should be able to see the
Linux text-based console rendered graphically, connecting to it via vnc.

Sorry for the basic question, but have you tried all the following?

vncviewer 127.0.0.1:0
vncviewer 127.0.0.1:1
vncviewer 127.0.0.1:2
vncviewer 127.0.0.1:5900
vncviewer 127.0.0.1:5901
vncviewer 127.0.0.1:5902

Given that from the xenstore-ls logs everything seems to work correctly
I am not sure what else to suggest. You might have to add printf to QEMU
ui/vnc.c and hw/display/xenfb.c to see what is going wrong.

Cheers,

Stefano

On Mon, 7 Nov 2022, Vipul Suneja wrote:
> Hi Stefano,
> Thanks!
>
> Any input further on "xenstore-ls" logs?
>
> I am trying to run the x0vncserver & x11vnc server manually on guest machine(xen_guest_image_minimal) image but it's failing with the below
> error.
>
> root@raspberrypi4-64:/usr/bin# x0vncserver
> x0vncserver: unable to open display ""
> root@raspberrypi4-64:/usr/bin#
> root@raspberrypi4-64:/usr/bin# x11vnc
> ###############################################################
> #@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@#
> #@ @#
> #@ ** WARNING ** WARNING ** WARNING ** WARNING ** @#
> #@ @#
> #@ YOU ARE RUNNING X11VNC WITHOUT A PASSWORD!! @#
> #@ @#
> #@ This means anyone with network access to this computer @#
> #@ may be able to view and control your desktop. @#
> #@ @#
> #@ >>> If you did not mean to do this Press CTRL-C now!! <<< @#
> #@ @#
> #@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@#
> #@ @#
> #@ You can create an x11vnc password file by running: @#
> #@ @#
> #@ x11vnc -storepasswd password /path/to/passfile @#
> #@ or x11vnc -storepasswd /path/to/passfile @#
> #@ or x11vnc -storepasswd @#
> #@ @#
> #@ (the last one will use ~/.vnc/passwd) @#
> #@ @#
> #@ and then starting x11vnc via: @#
> #@ @#
> #@ x11vnc -rfbauth /path/to/passfile @#
> #@ @#
> #@ an existing ~/.vnc/passwd file from another VNC @#
> #@ application will work fine too. @#
> #@ @#
> #@ You can also use the -passwdfile or -passwd options. @#
> #@ (note -passwd is unsafe if local users are not trusted) @#
> #@ @#
> #@ Make sure any -rfbauth and -passwdfile password files @#
> #@ cannot be read by untrusted users. @#
> #@ @#
> #@ Use x11vnc -usepw to automatically use your @#
> #@ ~/.vnc/passwd or ~/.vnc/passwdfile password files. @#
> #@ (and prompt you to create ~/.vnc/passwd if neither @#
> #@ file exists.) Under -usepw, x11vnc will exit if it @#
> #@ cannot find a password to use. @#
> #@ @#
> #@ @#
> #@ Even with a password, the subsequent VNC traffic is @#
> #@ sent in the clear. Consider tunnelling via ssh(1): @#
> #@ @#
> #@ http://www.karlrunge.com/x11vnc/#tunnelling @#
> #@ @#
> #@ Or using the x11vnc SSL options: -ssl and -stunnel @#
> #@ @#
> #@ Please Read the documentation for more info about @#
> #@ passwords, security, and encryption. @#
> #@ @#
> #@ http://www.karlrunge.com/x11vnc/faq.html#faq-passwd @#
> #@ @#
> #@ To disable this warning use the -nopw option, or put @#
> #@ 'nopw' on a line in your ~/.x11vncrc file. @#
> #@ @#
> #@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@#
> ###############################################################
> 09/03/2018 12:58:41 x11vnc version: 0.9.16 lastmod: 2019-01-05 pid: 424
> 09/03/2018 12:58:41 XOpenDisplay("") failed.
> 09/03/2018 12:58:41 Trying again with XAUTHLOCALHOSTNAME=localhost ...
> 09/03/2018 12:58:41
> 09/03/2018 12:58:41 *** XOpenDisplay failed. No -display or DISPLAY.
> 09/03/2018 12:58:41 *** Trying ":0" in 4 seconds. Press Ctrl-C to abort.
> 09/03/2018 12:58:41 *** 1 2 3 4
> 09/03/2018 12:58:45 XOpenDisplay(":0") failed.
> 09/03/2018 12:58:45 Trying again with XAUTHLOCALHOSTNAME=localhost ...
> 09/03/2018 12:58:45 XOpenDisplay(":0") failed.
> 09/03/2018 12:58:45 Trying again with unset XAUTHLOCALHOSTNAME ...
> 09/03/2018 12:58:45
>
> 09/03/2018 12:58:45 ***************************************
> 09/03/2018 12:58:45 *** XOpenDisplay failed (:0)
>
> *** x11vnc was unable to open the X DISPLAY: ":0", it cannot continue.
> *** There may be "Xlib:" error messages above with details about the failure.
>
> Some tips and guidelines:
>
> ** An X server (the one you wish to view) must be running before x11vnc is
> started: x11vnc does not start the X server. (however, see the -create
> option if that is what you really want).
>
> ** You must use -display <disp>, -OR- set and export your $DISPLAY
> environment variable to refer to the display of the desired X server.
> - Usually the display is simply ":0" (in fact x11vnc uses this if you forget
> to specify it), but in some multi-user situations it could be ":1", ":2",
> or even ":137". Ask your administrator or a guru if you are having
> difficulty determining what your X DISPLAY is.
>
> ** Next, you need to have sufficient permissions (Xauthority)
> to connect to the X DISPLAY. Here are some Tips:
>
> - Often, you just need to run x11vnc as the user logged into the X session.
> So make sure to be that user when you type x11vnc.
> - Being root is usually not enough because the incorrect MIT-MAGIC-COOKIE
> file may be accessed. The cookie file contains the secret key that
> allows x11vnc to connect to the desired X DISPLAY.
> - You can explicitly indicate which MIT-MAGIC-COOKIE file should be used
> by the -auth option, e.g.:
> x11vnc -auth /home/someuser/.Xauthority -display :0
> x11vnc -auth /tmp/.gdmzndVlR -display :0
> you must have read permission for the auth file.
> See also '-auth guess' and '-findauth' discussed below.
>
> ** If NO ONE is logged into an X session yet, but there is a greeter login
> program like "gdm", "kdm", "xdm", or "dtlogin" running, you will need
> to find and use the raw display manager MIT-MAGIC-COOKIE file.
> Some examples for various display managers:
>
> gdm: -auth /var/gdm/:0.Xauth
> -auth /var/lib/gdm/:0.Xauth
> kdm: -auth /var/lib/kdm/A:0-crWk72
> -auth /var/run/xauth/A:0-crWk72
> xdm: -auth /var/lib/xdm/authdir/authfiles/A:0-XQvaJk
> dtlogin: -auth /var/dt/A:0-UgaaXa
>
> Sometimes the command "ps wwwwaux | grep auth" can reveal the file location.
>
> Starting with x11vnc 0.9.9 you can have it try to guess by using:
>
> -auth guess
>
> (see also the x11vnc -findauth option.)
>
> Only root will have read permission for the file, and so x11vnc must be run
> as root (or copy it). The random characters in the filenames will of course
> change and the directory the cookie file resides in is system dependent.
>
> See also: http://www.karlrunge.com/x11vnc/faq.html
>
> Regards,
> Vipul Kumar
>
> On Thu, Nov 3, 2022 at 10:27 PM Vipul Suneja <vsuneja63@xxxxxxxxx> wrote:
> 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-ls
> tool = ""
> 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 <sstabellini@xxxxxxxxxx> 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 <sstabellini@xxxxxxxxxx> 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 <sstabellini@xxxxxxxxxx> 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
> > >
> > >
> > >
> >
> >
> >
>
>
>

Re: Porting Xen in raspberry pi4B