EMPTY_CONTEXT
pmap->pm_ctxnum = EMPTY_CONTEXT;
#define has_context(pmap) (((pmap)->pm_ctxnum != EMPTY_CONTEXT) == ((pmap) != kernel_pmap))
pmap->pm_ctxnum = EMPTY_CONTEXT;
pmap->pm_ctxnum = EMPTY_CONTEXT;
#define has_context(pmap) ((pmap)->pm_ctxnum != EMPTY_CONTEXT)
set_context(EMPTY_CONTEXT);
set_context(EMPTY_CONTEXT);
pmap->pm_ctxnum = EMPTY_CONTEXT;