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Re: Porting Xen in raspberry pi4B
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
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
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
> >
> >
> >
>
>
>
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