ktrwrite
ktrwrite(p, &kth, ktp, len);
ktrwrite(p, &kth, path, strlen(path));
ktrwrite(p, &kth, &kp, sizeof(kp));
error = ktrwrite(p, &kth, data, count);
ktrwrite(p, &kth, &kp, sizeof(kp));
ktrwrite(p, &kth, &kp, sizeof(kp));
int ktrwrite(struct proc *, struct ktr_header *, const void *, size_t);