NMI_STACK_SIZE
static char nmi0_stack[NMI_STACK_SIZE] __aligned(16);
np = ((struct nmi_pcpu *)&nmi_stack[NMI_STACK_SIZE]) - 1;
DOMAINSET_PREF(domain), NMI_STACK_SIZE, M_WAITOK | M_ZERO);
pmap_pti_add_kva_locked(va - NMI_STACK_SIZE, va, false);