Hello,
 
I tried to build genode with a l4linux on foc_x86_64 :
I found two issues:
1)  in the builddir I call simply 
         make run/l4linux
    and an error in dde_ipxe happend, that the "compiler.h" is not found.
     Solution: in dde_ipxe have to be called:
             make prepare
     ==> I suggest politely to add this hint in http://www.genode.org/documentation/platforms/foc (and the README) 
          since the README suggested to add the repository for dde_ipxe 
 
2) the
     make run/l4linux
   returns to errors, because the l4linux binary is not found.
   The problem is, that l4linux is not available for x86_64   
 
(This is no problem, I just want to document why it is not working.)
Greetings
   Rudolf Weber