[K12OSN] Fl_TeacherTool 0.30 issue (long)

Robert Arkiletian robark at gmail.com
Fri Jan 20 06:41:11 UTC 2006

I have pretty much finished a new version of TT. I have added the
requested monitor/control feature using the vnc.so module that plugs
into X on the client. So now we can not only broadcast but also
monitor students activity or tutor them controlling their keyboard and
mouse. I have done minimal testing and it seems to work fine. BTW one
nice feature is that the broadcasting is unaffected by this new
feature because the broadcast uses tightvncviewer not realvncviewer.

Here is the issue. It requires modifiying LTSP. The how-to on the ltsp wiki here


describes the procedure and I have also pasted a summary how-to of it
from Trond Maehlum  below.
However, Eric Harrison and I are concerned about libgcc_s.so.1 which is
being overwritten in /opt/ltsp/i382/lib with the one from /usr/lib in
K12LTSP. These two libraries are *not* the same size. Unfortunately,
vnc.so does not work with the client X server with the stock
libgcc library. One thing to note is that vnc.so gets loaded at boot
time or (ctrl-alt-bkspc) not runtime. The only way I can *think* of
solving this is to build the vnc.so module inside a chrooted ltsp
tree. So it gets built with the ltsp stock libgcc. But I don't know if
this is even possible or how to do it. Wondering if anyone has any
ideas how to solve this problem? I know that a sym link approach was
used to address this issue in the wiki but I don't think it's a real
solution (But I could be wrong).

Here is a summary how-to from Trond Maehlum
Login at the terminalserver as root. Edit /opt/ltsp/i386/etc/lts.conf
and add:

X4_MODULE_02 = vnc

Then edit the file /opt/ltsp/i386/etc/build_x4_cfg
 and add the following under 'Secton "Screen"' (but over
'EndSubSection'), so it looks
like this:

 Section "Screen"
       Identifier "Screen0"
       Device "My Video Card"
       Monitor "My Monitor"
       DefaultDepth  ${X_COLOR_DEPTH:-16}
       Subsection "Display"
               Depth ${X_COLOR_DEPTH:-16}
               Modes ${MODE[*]}

               Option "httpdir" "/usr/share/vnc/classes"
               Option "PasswordFile" "/root/.vnc/passwd"
               Option "rfbport" "5900"
               Option "usevnc"


Now you'll have to make a password for the vnc-session. Run this

# /usr/bin/vncpasswd

Choose a password and copy the password file into the ltsp-tree

# cp -R -p /root/.vnc /opt/ltsp/i386/root/

Now you must copy the vnc-module and some libraries into the ltsp-tree:

# cp /usr/X11R6/lib/modules/extensions/vnc.so
# cp /usr/lib/libstdc++.so.6 /opt/ltsp/i386/usr/lib/
Before you do this next cp. Backup /opt/ltsp/i386/lib/libgcc_s.so.1 as
so you don't lose the original file.
# cp /lib/libgcc_s.so.1 /opt/ltsp/i386/lib/
Robert Arkiletian
C++ GUI tutorial http://fltk.org/links.php?V19

More information about the K12OSN mailing list