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I am trying to trigger a bug, and to do that I need to run Xserver with VESA driver on top using 24bpp.

I have qemu VMs with all sorts of distors (Ubuntu, CentOS, Debian, OpenSUSE), so please feel free to answer my question in whatever fits you best.

So far, no luck... I trying to connect with VNCViewer:

From the server:

# vncserver :1
xauth:  file /root/.Xauthority does not exist

Creating default startup script /root/.vnc/xstartup
Starting applications specified in /root/.vnc/xstartup
Log file is /root/.vnc/vncserver:1.log

CConn:       connected to host xxx.xxx.xxx.xxx port 5901
 CConnection: Server supports RFB protocol version 3.8
 CConnection: Using RFB protocol version 3.8
 CConnection: Choosing security type VncAuth(2)

From the Client:

vncviewer hostname:1

Then, a window opens and I automatically get logged into gnome-session. At the same time, in the client terminal, I see:

Fri Jan  9 18:56:39 2015
 CConn:       Using pixel format depth 24 (32bpp) little-endian rgb888
 CConn:       Using Tight encoding
 CConn:       Enabling continuous updates

Fri Jan  9 18:56:49 2015
 CConn:       Throughput 2122 kbit/s - changing to quality 6
 CConn:       Using Tight encoding

So, as you can see it says: Using pixel format depth 24 (32bpp) little-endian rgb888 which is not what I want. I want 24bpp

Also, I would like to know how can I change the VGA driver and load vesa.

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I believe you need a Screen section in your xorg.conf file. If no xorg.conf file exists the server tries to guess the best rate, which in this case is 32 bpp, which is also the Max for most Graphics Adapters. I found this Example in the Linear Addressing Section of the Information for Tseng Chipset Users Guide (Even though the document says XFree86, the same applies to XOrg).

Section "screen"
    SubSection "Display"
        Depth 8
        Virtual 1280 1024
        ViewPort 0 0
        Modes "640x480" "800x600" "1024x768"
    EndSubSection
    SubSection "Display"
        Depth 16
        Virtual 1024 992
        ViewPort 0 0
        Modes "640x480" "800x600" "1024x768"
    EndSubSection
    SubSection "Display"
        Depth 24
        Virtual 960 720
        ViewPort 0 0
        Modes "640x480" "800x600"
    EndSubSection
    SubSection "Display"
        Depth 32
        Virtual 832 600
        ViewPort 0 0
        Modes "640x480" "800x600"
    EndSubSection
EndSection

Notice the Depth Setting. When Combined with the Modes Setting, you can manually set the resolution and Color Depth. See also the xorg.conf(5x) manual page.

  • Also, qemu doesn't use vesa lspci -vnn | grep VGA -A 12 00:02.0 VGA compatible controller [0300]: Cirrus Logic GD 5446 [1013:00b8] (prog-if 00 [VGA controller]) Do you know how to install VESA ? – drpaneas Jan 9 '15 at 18:53

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