Looks like Xen kernels can't build with LOCKDEBUG at present:

/Volumes/workspaces/nbeq/nbsrc/sys/arch/xen/i386/pmap.c: In function
'pmap_enter_ma':
/Volumes/workspaces/nbeq/nbsrc/sys/arch/xen/i386/pmap.c:3595: warning: passing
argument 1 of '_simple_lock' from incompatible pointer type
/Volumes/workspaces/nbeq/nbsrc/sys/arch/xen/i386/pmap.c:3597: warning: passing
argument 1 of '_simple_unlock' from incompatible pointer type
/Volumes/workspaces/nbeq/nbsrc/sys/arch/xen/i386/pmap.c:3675: warning: passing
argument 1 of '_simple_unlock' from incompatible pointer type
/Volumes/workspaces/nbeq/nbsrc/sys/arch/xen/i386/pmap.c:3678: warning: passing
argument 1 of '_simple_unlock' from incompatible pointer type
/Volumes/workspaces/nbeq/nbsrc/sys/arch/xen/i386/pmap.c:3689: warning: passing
argument 1 of '_simple_lock' from incompatible pointer type
/Volumes/workspaces/nbeq/nbsrc/sys/arch/xen/i386/pmap.c:3691: warning: passing
argument 1 of '_simple_unlock' from incompatible pointer type

Is this already widely known?

-- 
  Thor Lancelot Simon	                                     tls@rek.tjls.com

  "The inconsistency is startling, though admittedly, if consistency is to
   be abandoned or transcended, there is no problem."	      - Noam Chomsky