add_einfo
void add_einfo(char *, char *, bblk_hs_t *, uint32_t);
add_einfo(bblock->extra, updt_str, &hs, avail_space);
add_einfo(bblock->extra, updt_str, &hs, avail_space);
add_einfo(stage2->extra, updt_str, &hs, avail_space);
add_einfo(buf + extra, version, &hs, avail_space);