You are probably missing libloader.s.so in your build tree. This

library

comes from l4/pkg/loader/lib/runtime and should install to l4/lib/*/*/libloader.s.so. You also need to enable the option to build libloader.s.so in the configuration menu.

[Jayesh Salvi] You are right. Once I compiled L4Env and recompiled the l4linux2.6 it compiled successfully. Thanks.