Hi Alexander, They get generated as part of the compilation of the libsel4 library, which is separate to the kernel compilation. See the libsel4 Makefile (https://github.com/seL4/seL4/blob/master/libsel4/Makefile) Adrian On Wed 14-Jun-2017 1:32 AM, Alexander Boettcher wrote: Hello, if I compile and link seL4 5.2.0 ARCH=x86 PLAT=pc99 SEL4_ARCH=x86_64 make and I finally try to use the generated syscall/libsel4 headers, the compiler complains about missing seL4_Fault types and functions in libsel4/sel4_arch_include/x86_64/sel4/sel4_arch/faults.h like seL4_Fault_t seL4_Fault_tag seL4_Fault_VMFault_new and a lot more. These structs and functions seems to be generated only for the kernel side, e.g. in kernel_final.c they show up, but there are no traces of them on the user level side. Do I just miss a configuration option ? Thanks,