how to get higher screen resolutions for Linux-based HVMs

[Eric Shelton]

A lot of the time in an HVM, out of the box X11 fails to either use the QEMU VESA display adapter, or fails to recognize the full range of available resolutions because the emulated adapter does not provided EDID data.  However, this can generally be fixed by editing or creating /etc/X11/xorg.conf to include the following portions:

Section "Device"

    Identifier "device"

    Driver "vesa"

EndSection

Section "Monitor"

    Identifier "monitor"

    HorizSync 20.0 - 50.0

    VertRefresh 40.0 - 80.0

    Option "DPMS"

EndSection

Section "Screen"

    Identifier "screen"

    Device "device"

    Monitor "monitor"

    DefaultDepth 24

    Subsection "Display"

        Modes "1920x1200" "1680x1050" "1400x1050" "1024x768"

    EndSubsection

EndSection

Not every line of the above configuration may be needed, but it allowed me to take a Linux distro that initially only offered me 800x600 resolution, and now I am running it at 1920x1200.  Actually, it appears to offer all of the resolutions up to 1920x1200, and not just the four shown above.  Probably the "Device" and "Monitor" sections are the main factors in this working now, and it has little to do with the modes listed in the config file.

Best,

Eric

[Marek Marczykowski-Górecki]

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I think it is already documented here:
https://www.qubes-os.org/doc/LinuxHVMTips/

- --
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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[joev...@gmail.com]

When following the instructions in https://www.qubes-os.org/doc/LinuxHVMTips/ ... I do get the higher resolutions. So large, in fact it is too big. There are other resolutions now available to me.
But whatever I select, results in a screen that seems to have a sync problem. The video is scrambled, only the default resolution works (which is now too large).

Is there a fix for this?
I have tried setting HorizSync to many different values. This does result in different resolution options available in the menu... but the same problem of not being able to have a working resolution.

My HVM is Lubuntu 17.04

Thanks.