[K12OSN] K12LTSP - make install - Linux kernel source not found

[Leo Willems]

Dear all,

 thank you all for the K12LTSP distribution and keeping up the
 community with this mailing list.

 I use the K12LTSP(6.0.0) in server / thin-client setups for computer
 labs in children homes in South East Asia.
 I really appreciate the automatic detection of most of the hardware
 devices (video, audio, network) during the several installations.
 ...

 Currently I like to compile drivers for a Attansic L2 Fast Ethernet
 (onboard), the network card was not detected during the installation.

 I did this:

  tar zxf L2-linux-driver.tar.gz
  cd L2-linux-driver/rc/
  make install

 Error message: Linux kernel source not found. Stop.

 Questions:
 1. How to make sure the Linux kernel source are available?
 2. How to add the Linux kernel source on a running K12LSTP server?

 Thank you!
 Leo