[PC-BSD Testing] Overcoming VirtualBox's Miniature Screen Size in PCBSD VM

Ian Robinson fitchkendall at gmail.com
Tue Dec 22 15:28:11 PST 2009

Re:  Overcoming VirtualBox's Miniature Screen Size in PCBSD VM.

About ten days ago Ian Robinson asked:

> Here is a question about VirtualBox and its resolution. Since FreeBSD does
>not have a guest additions module, you are limited to using
>either a vesa driver or a VirtualBox Graphics Adapter from Innotek "fbdev."
> Generally, the higher the screen resolution, the larger the screen display

> (i.e., 1024x768 results in a bigger screen than 800x600).
>Both seem to be limited to a max of 1024x768.
>However, here is the rub -- Kris' PCBSD video driver routine
>used to configure X during the 1st reboot produces an even larger
> Screen than 1024x768.? How does Kris do this? What driver, what settings?

Kris Moore replied.


Actually I'm pretty sure its just the vesa driver, and it sets some monitor
values to try and force xorg to run in a higher res. If you play with it,
check /etc/X11/xorg.conf afterwards and you can get examples of
what its doing. Or when the XGUI comes up, right click, bring up xterm,
and look at the /etc/X11/xorg.conf there to see what its doing as well.

Kris Moore
PC-BSD Software

1.  Analysis:  Kris' video configuration routine boots using
/root/xorg.conf.new.  The resulting configuration file is stored in
/etc/X11/xorg.conf.  The biggest difference between the two is that Kris
uses a depth of 16 instead of 24.  Consequently, the "depth" variable plays
a critical role in the resulting size of the PCBSD virtual machine.

2.  Thanks to a post found at:


There, the author discusses his technique for enlarging the VirtualBox
window, and I followed most of his advice and most of his settings.
to get my Virtualbox screen to adapt to a new size, I never had to invoke
the command line:

VBoxManage setextradata [VM-name] CustomVideoMode1 [WxHxBPP]

3.  What I did is combine the PCBSD xorg.conf and the author's xorg.conf.
For example, one of the obvious differences is that PCBSD keeps its font
libraries in a different location than the author's system.  Here is the
complete configuration I ended up with (and which you can copy into a text
editor & save as xorg.conf) to get a Virtualbox display covering about 7/8
of my screen:

# Xorg.conf file generated for PC-BSD

Section "ServerLayout"
    Identifier     "XFree86 Configured"
    Screen      0  "Screen0" 0 0
    InputDevice    "Mouse0" "CorePointer"
    InputDevice    "Keyboard0" "CoreKeyboard"
    Option       "Clone" "off"

Section "ServerFlags"
        Option "AutoAddDevices" "False"
        Option "AllowEmptyInput" "Off"

Section "Files"
    ModulePath      "/usr/local/lib/xorg/modules"
    FontPath        "/Programs/fonts/"
    FontPath        "/usr/local/lib/X11/fonts/cyrillic/"
    FontPath        "/usr/local/lib/X11/fonts/TrueType/"
    FontPath        "/usr/local/lib/X11/fonts/webfonts/"
    FontPath        "/usr/local/lib/X11/fonts/misc/"
    FontPath        "/usr/local/lib/X11/fonts/TTF/"
    FontPath        "/usr/local/lib/X11/fonts/Type1/"
    FontPath        "/usr/local/lib/X11/fonts/CID/"
    FontPath        "/usr/local/lib/X11/fonts/75dpi/"
    FontPath        "/usr/local/lib/X11/fonts/100dpi/"
    FontPath        "/usr/local/lib/X11/fonts/dejavu/"
    FontPath        "/usr/local/lib/X11/fonts/local/"

Section "Module"
    Load           "dbe"
    Load           "dri"
    Load           "ddc"
    Load           "extmod"
    Load           "glx"
    Load           "xtrap"
    Load           "freetype"

Section "InputDevice"
    Identifier     "Keyboard0"
    Driver         "keyboard"
    Option         "XkbModel" "pc105"
    Option         "XkbLayout" "us"
    Option         "XkbVariant" ""

Section "InputDevice"
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/sysmouse"
    Option         "Buttons" "6"
    Option         "ZAxisMapping" "4 5"
    Option         "Emulate3Buttons"

Section "Monitor"
    Identifier     "Monitor0"
    HorizSync      31-80
    VertRefresh    30-100
    VendorName     "Monitor Vendor"
    ModelName      "Monitor Model"

Section "Device"
    Identifier      "Card0"
    Screen           0
    Driver         "vesa"
    VendorName     "Generic Vesa Driver"
    BusID      "PCI:0:2:0"

Section "Screen"
    Identifier     "Screen0"
    Device         "Card0"
    Monitor        "Monitor0"
    DefaultDepth   16
    SubSection     "Display"
        Viewport   0 0
        Depth      16
        Modes      "1280x800"

REMEMBER -- Back up your virtual machine's existing xorg.conf.
REMEMBER -- You will have to have root privileges to save this new file in
(or in place of)  /etc/X11/xorg.conf

Ian Robinson
Salem, Ohio
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