nvp_cksum
hdrsum = nvp_cksum((uchar_t *)&hdr, sizeof (hdr));
cksum = nvp_cksum((uchar_t *)buf, hdr.nvpf_size);
((nvpf_hdr_t *)buf)->nvpf_chksum = nvp_cksum((uchar_t *)nvbuf, buflen);
nvp_cksum((uchar_t *)buf, sizeof (nvpf_hdr_t));