Re: XL Console: Accessing DomU Guis?

["John L. Poole" <jlpoole56@xxxxxxxxx>]

Paul, thank you for your responses and consideration of my issue.

I just want to confirm I am trying to follow the desired protocol
for email responses as outlined at:
https://xenproject.org/help/mailing-list/

    Post in plain text (i.e. not HTML), word-wrapped to somewhere
    around 72 characters.

    Don’t top-post: reply in-line below the text you’re replying to.

    Trim the quoted material in your reply to only include the bits
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I am responding to your responses inline below.
On 1/4/2024 1:48 AM, Paul Leiber wrote:
> <snip>
> I assume from what you have written that you are running a
> TigerVNC server
> instance in the DomU. If you use the VNC option built into Xen
> (provided via QEMU, I belive), you don't need to use TigerVNC
> on the DomU.

I found this statement as SUSE's site under the section entitled
"Managing Virtual Machines with Xen":

   22.3.2 Using SDL instead of a VNC Viewer

   If you access a virtual machine's display from the virtual
   machine host console (known as local or on-box access),
   you should use SDL instead of VNC viewer.
   VNC viewer is faster for viewing desktops over a network,
   but SDL is faster for viewing desktops from the same computer.

   Source:
https://documentation.suse.com/sles/12-SP5/html/SLES-all/cha-xen-config.html

> <snip>
> My understanding is that the Dom0 _console_ simply can't display
> the GUI from the DomU. "xl console" does what it says, it shows
> the console of the DomU. The output of the DomU console after starting
> xinit shows that this is working as intended. "xl create" with
> the "-c" option is equivalent to using "xl console". Also, a Dom0
> console is not "activated" by the DomU in any way, I think a DomU
> influencing the Dom0 in such a way would violate the security aspect
> of virtualization.
Correct.  I have not be careful with my terminology.  What I envision
is running Xfce in Dom0 as user jlpoole, and then within the Xfce
session, launching a console within and executing the command:
"sudo xl console [X]".  This procedure should be distinguished
from being in the console window at boot time and trying therein
"sudo xl console [X]" where I am not operating over an
already-launched gui.

>
> GUI content from the DomU, be it transmitted via VNC or SDL or

> whatever, needs to be shown in a separate window in a GUI.
> Also, your Xfce desktop will not be "replaced" by anything.
> Xfce still is required for Dom0 to be able to render the windows
> in which the DomU GUI is shown.
Agreed.
>
> If you have two DomUs you want to switch between (e. g. your
> Linux/KDE and your Windows DomU), you will have two separate
> Windows in your Dom0 Xfce GUI between which you can switch.
Yes, agreed.
>
>> Xorg log file from an attempt to launch xinitc. In a prior attempt, I
>> waited 3 minutes after output on the display before I executed
>> Control-C; in this log, I only waited for about 20 seconds:
>>
>> https://salemdata.us/xen/guis/Xorg.0._20240103_1741PST.log
>>
>> I believe the ability to access the guis from Dom0 would be achieved by
>> selecting SDL in the configuration and executing the "xl console"
>> command from within a console on a gui. From my configurations file,
>> ryzdesk.conf:
>>
>>
>>     ...
>>     vfb = [ 'type=sdl' ]
>>     ...
>>     # ref: https://www.youtube.com/watch?v=s1Ro0KxHooQ
>>     #
>>     videoram=16
>>     stdvga=1
>>     sdl = 1
>>     vnc = 0
>
>
> Two aspects come to my mind here:
>
> 1) There seem to be different options for SDL depending on the
> type of the DomU (PV or HVM).
> You seem to be setting options for both versions. Perhaps
> they get in the way of each other?
> See here: https://xenbits.xen.org/docs/unstable/man/xl.cfg.5.html

I will look into this more and try to figure out the nuances.
I was hoping by posting here I might garner the attention
of somebody who runs the kind of configuration I want to do
and I would be directed with some simple instructions or
someone would point out what I have missed or overlooked.
>
> 2) In the video you referenced, my point from above is
> confirmed: With starting the DomU, a separate X window
> opens automatically, the GUI of the DomU is _not_ shown
> in the terminal window. In fact, no "xl console" is ever executed.

Correct.  I tried to launch my Windows 7 ISO, but have run into
other problems with my qemu complaining about being unable
to find i386 stuff... I think it is a bug Gentoo's distribution
has caused and need to file a bug according for the
file complained of is, in fact, present on my system, it just
is in another directory.
Gentoo often has these kind of change-the-directory to suit Gentoo's
philosophy and then some other software expect to find a file in a
directory where Gentoo's installer changed it.
> <snip>
> Do the Xen/QEMU logs on your Dom0 say anything relevant,
> e. g. about failing to start SDL?
>
I did not see anything.
<snip>

John