we get much futher now when building ntdll on cygwin. when linking I am getting the following error ntdll.exp(.edata+0xe4c):fake: undefined reference to `NTDLL_alloca_probe at 0' ntdll.exp(.edata+0xe5c):fake: undefined reference to `NTDLL_chkstk at 0' there are some other warnings but this is the only major thing with ntdll. Thanks Steven