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Re: [Qemu-discuss] VGA choices

From: Narcis Garcia
Subject: Re: [Qemu-discuss] VGA choices
Date: Wed, 1 Feb 2017 15:20:01 +0100

Qemu will provide some graphics adaptor to guest anyway. If you don't specify one, Qemu will use whatever default is for your version.

I use "-vga qxl" with the hope it's the less resources consuming if guest is not asking much.

I've tried this now and a resolution is proposed by Qemu when guest OS asks for frame buffers. You could press [Enter] if you wanted to provide FB, but it will be asked on boot while (in theory) you aren't configuring guest boot to not ask FB.


(Current Debian needs: install vga=normal fb=false)

I don't know how to specify Qemu a resolution or FB selection.

El 01/02/17 a les 13:25, Vincenzo Romano ha escrit:
I've tried to start a previously created VM (running Ubuntu Server
16.04) with just " -nographic -curses" as far as the console is
So, no "-vga" and no "-vnc" option. And no -daemonize of course.
The PTY shows immediately a black screen with a blue "800 x 600
Graphic mode" in the center... and then nothing else, despite I have
asked for a "splash-time=5".
I think the BIOS itself is preventing the curses mode to work. How can
I "fix"this?
Vincenzo Romano - NotOrAnd.IT
Information Technologies

2017-02-01 11:45 GMT+01:00 Vincenzo Romano <address@hidden>:
What you say, Narcis, makes sense. And a lot of it.
I will make a few tests to "engineer" a stable solution with curses,
as VNC is already working out-of-the-box.
The main problem is to run a dozen of VMs each with its own
screen/tmux/byobu session and to be able
to select the right one.

With VNC, SSH and different loopback addresses this is trivial.


Vincenzo Romano - NotOrAnd.IT
Information Technologies

2017-02-01 11:35 GMT+01:00 Narcis Garcia <address@hidden>:
Any text display should be lighter than any graphic one.
I got most of details from: 1 Documentation, 2 Lists&forums, 3 try and

El 01/02/17 a les 10:48, Vincenzo Romano ha escrit:
Hi Narcis,

Thank you for the extra details: the documentation is quite terse if
not insufficient.
I mean: https://qemu.weilnetz.de/doc/qemu-doc.html linked as the
official user manual from

According to your experience, which approach is the "lightest" among
"-display vnc" and "-ncurses"?

Finally, may I ask you where did you pull these details from?

Thanks again.
Vincenzo Romano - NotOrAnd.IT
Information Technologies

2017-02-01 9:23 GMT+01:00 Narcis Garcia <address@hidden>:
-nographic cannot be combined with any other -display.
As far as I know, Curses go to local stdout; you can see easily when you
lauch Qemu from command line and, by intuition I supose that, (same as
SDL) closing the stdout channel/terminal Qemu process can be closed too.

You could launch Qemu process in a "screen" session, and attach remotely
to it when you connect through SSH.

El 01/02/17 a les 08:51, Vincenzo Romano ha escrit:
Thanks, Narcis.

2017-02-01 8:29 GMT+01:00 Narcis Garcia <address@hidden>:
VNC is a protocol to connect to a GUI, not MDA/TXT.
Independently of what guest OS does or shows, Qemu only outputs display
- VNC (graphic)

- SDL (graphic)
Local to the host

- GTK (graphic)
Local to the host (maybe also networked with X11)

- Curses (text)

- none (no display)
None, indeed.

My host is a headless server and I'd like to save all resources I can
from it to give them to the guests.
So I need remote access to the guests that I would like to do with
(the latter two with SSH tunnels).

VNC seems to me a solution, but I couldn't find enough details about
the curses solution which
would be my preferred solution because of its low requirements.
Where is the ncurses output pushed to? A local PTY? A Unix socket?

Why cannot I use -nographic with -daemonize (and VNC)?

El 31/01/17 a les 21:14, Vincenzo Romano ha escrit:
Thanks for the feedback.

I need to have a text mode console to the server via VNC (or actually
whatever else) in case the network is not working or to operate on the
BIOS and the boot loader.
And I would like to have such a thing as lean as possible to save
resources on the host.
As of now I am using "-vga virtio" that is a full blown VGA. I am
thinking about a PC with just 80x25 screen.

Vincenzo Romano - NotOrAnd.IT
Information Technologies

2017-01-31 19:47 GMT+01:00 A. Wan <address@hidden>:
On Tue, January 31, 2017 09:54, Vincenzo Romano wrote:
Sorry for the typo:


Il 31 gen 2017 18:48, "Vincenzo Romano" <address@hidden> ha

Hi all.
I need to create a number of VM to be used as Linux servers.
I am planning to use only a VNC console.
Can I disable the VGA settings (-vga none) and only use the BBC server?
If not, what's the minimal (as far as the host resources are concerned)
configuration for the local text-only console via VNC?


I don't think it is possible to VNC to text mode console.  Is there a reason
why you don't want to telnet/ssh to a guest and then run screen?









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