mdb_pread() and mdb_pwrite()

ssize_t mdb_pread(void *buf, size_t nbytes, uint64_t addr);
ssize_t mdb_pwrite(const void *buf, size_t nbytes, uint64_t addr);

These functions provide the ability to read and write data from a given target physical address, specified by the addr parameter. The mdb_pread() function returns nbytes for success, or -1 for error; if a read is truncated because only a portion of the data can be read from the specified address, -1 is returned. The mdb_pwrite() function returns the number of bytes actually written upon success; -1 is returned upon error.