IREENT_MAGIC
if ((err == 0 || err == IREENT_MAGIC)
cmpq $IREENT_MAGIC,(TF_ERR+8)(%rsp) ;\
if ((err == 0 || err == IREENT_MAGIC) && trapno == T_ASTFLT) {
cmpl $IREENT_MAGIC,(TF_ERR+4)(%eax) ;\