KTR_USER_MAXLEN
buf = MMAP(KTR_USER_MAXLEN, 0);
len = vsnprintf(buf + filled, KTR_USER_MAXLEN - filled, format, ap);
if ((size_t)len > KTR_USER_MAXLEN - filled)
len = KTR_USER_MAXLEN - filled;
if (filled == KTR_USER_MAXLEN || buf[filled - 1] == '\n') {
if (len > KTR_USER_MAXLEN)
char visbuf[4 * KTR_USER_MAXLEN + 1];