Attached is a patch that adds 4-level page table support to the IA-64 architecture. I followed the way PPC used the machdep command line argument to force it. Since this is truly a CONFIG option on IA-64, I have also added a routine to parse the required information out of IKCONFIG if it's available. I'm thinking about requiring IKCONFIG for LKCD, because it just makes life easer. As a side note, I decided I hate how everything is piled into defs.h and separated by ifdefs. Dave, how do you feel about breaking defs.h up into a header for each arch, i.e. ia64_defs.h, ppc_def.h, etc, and a small common defs.h? Thanks, Troy