This is an unnamed and undocumented partition table format implemented by the bootloader and kernel that Amlogic provides for their Linux SoCs (Meson series at least, and probably others). They appear to use this rather than GPT, the industry standard, because their BootROM loads and executes the next stage loader from offset 512 (0x200) on the eMMC, which is exactly where the GPT header would have to start. So instead of changing their BootROM, Amlogic devised this partition table, which lives at an offset of 36MiB (0x240_0000) on the eMMC and so doesn't conflict. This parser expects as input just the partition table from that offset. The maximum number of partitions in a table is 32, which corresponds to a maximum table size of 1304 bytes (0x518).
This page hosts a formal specification of Amlogic proprietary eMMC partition table using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.
The Python runtime library can be installed from PyPI:
python3 -m pip install kaitaistructParse a local file and get structure in memory:
data = AmlogicEmmcPartitions.from_file("path/to/local/file.bin")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = AmlogicEmmcPartitions(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.checksum # => To calculate this, treat the first (and only the first) partition
descriptor in the table below as an array of unsigned little-endian
32-bit integers. Sum all those integers mod 2^32, then multiply the
result by the total number of partitions, also mod 2^32. Amlogic
likely meant to include all the partition descriptors in the sum,
but their code as written instead repeatedly loops over the first
one, once for each partition in the table.
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 9):
raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))
class AmlogicEmmcPartitions(KaitaiStruct):
"""This is an unnamed and undocumented partition table format implemented by
the bootloader and kernel that Amlogic provides for their Linux SoCs (Meson
series at least, and probably others). They appear to use this rather than GPT,
the industry standard, because their BootROM loads and executes the next stage
loader from offset 512 (0x200) on the eMMC, which is exactly where the GPT
header would have to start. So instead of changing their BootROM, Amlogic
devised this partition table, which lives at an offset of 36MiB (0x240_0000)
on the eMMC and so doesn't conflict. This parser expects as input just the
partition table from that offset. The maximum number of partitions in a table
is 32, which corresponds to a maximum table size of 1304 bytes (0x518).
.. seealso::
Source - http://aml-code.amlogic.com/kernel/common.git/tree/include/linux/mmc/emmc_partitions.h?id=18a4a87072ababf76ea08c8539e939b5b8a440ef
.. seealso::
Source - http://aml-code.amlogic.com/kernel/common.git/tree/drivers/amlogic/mmc/emmc_partitions.c?id=18a4a87072ababf76ea08c8539e939b5b8a440ef
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.magic = self._io.read_bytes(4)
if not self.magic == b"\x4D\x50\x54\x00":
raise kaitaistruct.ValidationNotEqualError(b"\x4D\x50\x54\x00", self.magic, self._io, u"/seq/0")
self.version = (KaitaiStream.bytes_terminate(self._io.read_bytes(12), 0, False)).decode(u"UTF-8")
self.num_partitions = self._io.read_s4le()
if not self.num_partitions >= 1:
raise kaitaistruct.ValidationLessThanError(1, self.num_partitions, self._io, u"/seq/2")
if not self.num_partitions <= 32:
raise kaitaistruct.ValidationGreaterThanError(32, self.num_partitions, self._io, u"/seq/2")
self.checksum = self._io.read_u4le()
self.partitions = []
for i in range(self.num_partitions):
self.partitions.append(AmlogicEmmcPartitions.Partition(self._io, self, self._root))
class Partition(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.name = (KaitaiStream.bytes_terminate(self._io.read_bytes(16), 0, False)).decode(u"UTF-8")
self.size = self._io.read_u8le()
self.offset = self._io.read_u8le()
self._raw_flags = self._io.read_bytes(4)
_io__raw_flags = KaitaiStream(BytesIO(self._raw_flags))
self.flags = AmlogicEmmcPartitions.Partition.PartFlags(_io__raw_flags, self, self._root)
self.padding = self._io.read_bytes(4)
class PartFlags(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.is_code = self._io.read_bits_int_le(1) != 0
self.is_cache = self._io.read_bits_int_le(1) != 0
self.is_data = self._io.read_bits_int_le(1) != 0