PMAP_MAX_NASID
#define PMAP_ASID_MASK (PMAP_MAX_NASID - 1)
uint32_t pmap_asid[PMAP_MAX_NASID / 32];
unsigned long pmap_asid_gen = PMAP_MAX_NASID;
gen = atomic_add_long_nv(&pmap_asid_gen, PMAP_MAX_NASID);