Xen project Mailing List

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