generate_command_line_for_tree
Description:
[ Version ( since = "1.6.0" ) ]
public string generate_command_line_for_tree (Tree tree, InstallConfig config)
  public string generate_command_line_for_tree (Tree tree, InstallConfig config)
Some install scripts need to pass a command line to the kernel, Such install scripts belong to OSs that provide paths to the kernel and initrd files that can be used to directly boot (http://wiki.
qemu.org/download/qemu-doc.html#direct_005flinux_005fboot) the OS in order to pass the needed commandline to it.
The tree tree must have been identified successfully using 
        identify_tree() before calling this function.
Parameters:
| this | 
           the install script  | 
      
| tree | 
           the tree  | 
      
| config | 
           the install script config  | 
      
Returns:
| 
           The generated command line string, NULL otherwise.  |