mdb_tgt_fread
mdb_partial_xread, (void *)mdb_tgt_fread);
if (mdb_tgt_fread(mdb.m_target, buf, nbytes, addr) != nbytes)
ssize_t rbytes = mdb_tgt_fread(mdb.m_target, buf, nbytes, addr);
extern ssize_t mdb_tgt_fread(mdb_tgt_t *, void *, size_t, uintptr_t);