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.
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
import io.kaitai.struct.ByteBufferKaitaiStream;
import io.kaitai.struct.KaitaiStruct;
import io.kaitai.struct.KaitaiStream;
import java.io.IOException;
import java.util.Arrays;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.nio.charset.Charset;
import io.kaitai.struct.ConsistencyError;
import java.util.Objects;
import java.util.List;
/**
* 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).
* @see <a href="http://aml-code.amlogic.com/kernel/common.git/tree/include/linux/mmc/emmc_partitions.h?id=18a4a87072ababf76ea08c8539e939b5b8a440ef">Source</a>
* @see <a href="http://aml-code.amlogic.com/kernel/common.git/tree/drivers/amlogic/mmc/emmc_partitions.c?id=18a4a87072ababf76ea08c8539e939b5b8a440ef">Source</a>
*/
public class AmlogicEmmcPartitions extends KaitaiStruct.ReadWrite {
public static AmlogicEmmcPartitions fromFile(String fileName) throws IOException {
return new AmlogicEmmcPartitions(new ByteBufferKaitaiStream(fileName));
}
public AmlogicEmmcPartitions() {
this(null, null, null);
}
public AmlogicEmmcPartitions(KaitaiStream _io) {
this(_io, null, null);
}
public AmlogicEmmcPartitions(KaitaiStream _io, KaitaiStruct.ReadWrite _parent) {
this(_io, _parent, null);
}
public AmlogicEmmcPartitions(KaitaiStream _io, KaitaiStruct.ReadWrite _parent, AmlogicEmmcPartitions _root) {
super(_io);
this._parent = _parent;
this._root = _root == null ? this : _root;
}
public void _read() {
this.magic = this._io.readBytes(4);
if (!(Arrays.equals(this.magic, new byte[] { 77, 80, 84, 0 }))) {
throw new KaitaiStream.ValidationNotEqualError(new byte[] { 77, 80, 84, 0 }, this.magic, this._io, "/seq/0");
}
this.version = new String(KaitaiStream.bytesTerminate(this._io.readBytes(12), (byte) 0, false), StandardCharsets.UTF_8);
this.numPartitions = this._io.readS4le();
if (!(this.numPartitions >= 1)) {
throw new KaitaiStream.ValidationLessThanError(1, this.numPartitions, this._io, "/seq/2");
}
if (!(this.numPartitions <= 32)) {
throw new KaitaiStream.ValidationGreaterThanError(32, this.numPartitions, this._io, "/seq/2");
}
this.checksum = this._io.readU4le();
this.partitions = new ArrayList<Partition>();
for (int i = 0; i < numPartitions(); i++) {
Partition _t_partitions = new Partition(this._io, this, _root);
try {
_t_partitions._read();
} finally {
this.partitions.add(_t_partitions);
}
}
_dirty = false;
}
public void _fetchInstances() {
for (int i = 0; i < this.partitions.size(); i++) {
this.partitions.get(((Number) (i)).intValue())._fetchInstances();
}
}
public void _write_Seq() {
_assertNotDirty();
this._io.writeBytes(this.magic);
this._io.writeBytesLimit((this.version).getBytes(Charset.forName("UTF-8")), 12, (byte) 0, (byte) 0);
this._io.writeS4le(this.numPartitions);
this._io.writeU4le(this.checksum);
for (int i = 0; i < this.partitions.size(); i++) {
this.partitions.get(((Number) (i)).intValue())._write_Seq(this._io);
}
}
public void _check() {
if (this.magic.length != 4)
throw new ConsistencyError("magic", 4, this.magic.length);
if (!(Arrays.equals(this.magic, new byte[] { 77, 80, 84, 0 }))) {
throw new KaitaiStream.ValidationNotEqualError(new byte[] { 77, 80, 84, 0 }, this.magic, null, "/seq/0");
}
if ((this.version).getBytes(Charset.forName("UTF-8")).length > 12)
throw new ConsistencyError("version", 12, (this.version).getBytes(Charset.forName("UTF-8")).length);
if (KaitaiStream.byteArrayIndexOf((this.version).getBytes(Charset.forName("UTF-8")), ((byte) 0)) != -1)
throw new ConsistencyError("version", -1, KaitaiStream.byteArrayIndexOf((this.version).getBytes(Charset.forName("UTF-8")), ((byte) 0)));
if (!(this.numPartitions >= 1)) {
throw new KaitaiStream.ValidationLessThanError(1, this.numPartitions, null, "/seq/2");
}
if (!(this.numPartitions <= 32)) {
throw new KaitaiStream.ValidationGreaterThanError(32, this.numPartitions, null, "/seq/2");
}
if (this.partitions.size() != numPartitions())
throw new ConsistencyError("partitions", numPartitions(), this.partitions.size());
for (int i = 0; i < this.partitions.size(); i++) {
if (!Objects.equals(this.partitions.get(((Number) (i)).intValue())._root(), _root()))
throw new ConsistencyError("partitions", _root(), this.partitions.get(((Number) (i)).intValue())._root());
if (!Objects.equals(this.partitions.get(((Number) (i)).intValue())._parent(), this))
throw new ConsistencyError("partitions", this, this.partitions.get(((Number) (i)).intValue())._parent());
}
_dirty = false;
}
public static class Partition extends KaitaiStruct.ReadWrite {
public static Partition fromFile(String fileName) throws IOException {
return new Partition(new ByteBufferKaitaiStream(fileName));
}
public Partition() {
this(null, null, null);
}
public Partition(KaitaiStream _io) {
this(_io, null, null);
}
public Partition(KaitaiStream _io, AmlogicEmmcPartitions _parent) {
this(_io, _parent, null);
}
public Partition(KaitaiStream _io, AmlogicEmmcPartitions _parent, AmlogicEmmcPartitions _root) {
super(_io);
this._parent = _parent;
this._root = _root;
}
public void _read() {
this.name = new String(KaitaiStream.bytesTerminate(this._io.readBytes(16), (byte) 0, false), StandardCharsets.UTF_8);
this.size = this._io.readU8le();
this.offset = this._io.readU8le();
this._raw_flags = this._io.readBytes(4);
KaitaiStream _io__raw_flags = new ByteBufferKaitaiStream(this._raw_flags);
this.flags = new PartFlags(_io__raw_flags, this, _root);
this.flags._read();
this.padding = this._io.readBytes(4);
_dirty = false;
}
public void _fetchInstances() {
this.flags._fetchInstances();
}
public void _write_Seq() {
_assertNotDirty();
this._io.writeBytesLimit((this.name).getBytes(Charset.forName("UTF-8")), 16, (byte) 0, (byte) 0);
this._io.writeU8le(this.size);
this._io.writeU8le(this.offset);
final KaitaiStream _io__raw_flags = new ByteBufferKaitaiStream(4);
this._io.addChildStream(_io__raw_flags);
{
long _pos2 = this._io.pos();
this._io.seek(this._io.pos() + (4));
final Partition _this = this;
_io__raw_flags.setWriteBackHandler(new KaitaiStream.WriteBackHandler(_pos2) {
@Override
protected void write(KaitaiStream parent) {
_this._raw_flags = _io__raw_flags.toByteArray();
if (_this._raw_flags.length != 4)
throw new ConsistencyError("raw(flags)", 4, _this._raw_flags.length);
parent.writeBytes(_this._raw_flags);
}
});
}
this.flags._write_Seq(_io__raw_flags);
this._io.writeBytes(this.padding);
}
public void _check() {
if ((this.name).getBytes(Charset.forName("UTF-8")).length > 16)
throw new ConsistencyError("name", 16, (this.name).getBytes(Charset.forName("UTF-8")).length);
if (KaitaiStream.byteArrayIndexOf((this.name).getBytes(Charset.forName("UTF-8")), ((byte) 0)) != -1)
throw new ConsistencyError("name", -1, KaitaiStream.byteArrayIndexOf((this.name).getBytes(Charset.forName("UTF-8")), ((byte) 0)));
if (!Objects.equals(this.flags._root(), _root()))
throw new ConsistencyError("flags", _root(), this.flags._root());
if (!Objects.equals(this.flags._parent(), this))
throw new ConsistencyError("flags", this, this.flags._parent());
if (this.padding.length != 4)
throw new ConsistencyError("padding", 4, this.padding.length);
_dirty = false;
}
public static class PartFlags extends KaitaiStruct.ReadWrite {
public static PartFlags fromFile(String fileName) throws IOException {
return new PartFlags(new ByteBufferKaitaiStream(fileName));
}
public PartFlags() {
this(null, null, null);
}
public PartFlags(KaitaiStream _io) {
this(_io, null, null);
}
public PartFlags(KaitaiStream _io, AmlogicEmmcPartitions.Partition _parent) {
this(_io, _parent, null);
}
public PartFlags(KaitaiStream _io, AmlogicEmmcPartitions.Partition _parent, AmlogicEmmcPartitions _root) {
super(_io);
this._parent = _parent;
this._root = _root;
}
public void _read() {
this.isCode = this._io.readBitsIntLe(1) != 0;
this.isCache = this._io.readBitsIntLe(1) != 0;
this.isData = this._io.readBitsIntLe(1) != 0;
_dirty = false;
}
public void _fetchInstances() {
}
public void _write_Seq() {
_assertNotDirty();
this._io.writeBitsIntLe(1, (this.isCode ? 1 : 0));
this._io.writeBitsIntLe(1, (this.isCache ? 1 : 0));
this._io.writeBitsIntLe(1, (this.isData ? 1 : 0));
}
public void _check() {
_dirty = false;
}
private boolean isCode;
private boolean isCache;
private boolean isData;
private AmlogicEmmcPartitions _root;
private AmlogicEmmcPartitions.Partition _parent;
public boolean isCode() { return isCode; }
public void setIsCode(boolean _v) { _dirty = true; isCode = _v; }
public boolean isCache() { return isCache; }
public void setIsCache(boolean _v) { _dirty = true; isCache = _v; }
public boolean isData() { return isData; }
public void setIsData(boolean _v) { _dirty = true; isData = _v; }
public AmlogicEmmcPartitions _root() { return _root; }
public void set_root(AmlogicEmmcPartitions _v) { _dirty = true; _root = _v; }
public AmlogicEmmcPartitions.Partition _parent() { return _parent; }
public void set_parent(AmlogicEmmcPartitions.Partition _v) { _dirty = true; _parent = _v; }
}
private String name;
private long size;
private long offset;
private PartFlags flags;
private byte[] padding;
private AmlogicEmmcPartitions _root;
private AmlogicEmmcPartitions _parent;
private byte[] _raw_flags;
public String name() { return name; }
public void setName(String _v) { _dirty = true; name = _v; }
public long size() { return size; }
public void setSize(long _v) { _dirty = true; size = _v; }
/**
* The start of the partition relative to the start of the eMMC, in bytes
*/
public long offset() { return offset; }
public void setOffset(long _v) { _dirty = true; offset = _v; }
public PartFlags flags() { return flags; }
public void setFlags(PartFlags _v) { _dirty = true; flags = _v; }
public byte[] padding() { return padding; }
public void setPadding(byte[] _v) { _dirty = true; padding = _v; }
public AmlogicEmmcPartitions _root() { return _root; }
public void set_root(AmlogicEmmcPartitions _v) { _dirty = true; _root = _v; }
public AmlogicEmmcPartitions _parent() { return _parent; }
public void set_parent(AmlogicEmmcPartitions _v) { _dirty = true; _parent = _v; }
public byte[] _raw_flags() { return _raw_flags; }
public void set_raw_Flags(byte[] _v) { _dirty = true; _raw_flags = _v; }
}
private byte[] magic;
private String version;
private int numPartitions;
private long checksum;
private List<Partition> partitions;
private AmlogicEmmcPartitions _root;
private KaitaiStruct.ReadWrite _parent;
public byte[] magic() { return magic; }
public void setMagic(byte[] _v) { _dirty = true; magic = _v; }
public String version() { return version; }
public void setVersion(String _v) { _dirty = true; version = _v; }
public int numPartitions() { return numPartitions; }
public void setNumPartitions(int _v) { _dirty = true; numPartitions = _v; }
/**
* 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.
*/
public long checksum() { return checksum; }
public void setChecksum(long _v) { _dirty = true; checksum = _v; }
public List<Partition> partitions() { return partitions; }
public void setPartitions(List<Partition> _v) { _dirty = true; partitions = _v; }
public AmlogicEmmcPartitions _root() { return _root; }
public void set_root(AmlogicEmmcPartitions _v) { _dirty = true; _root = _v; }
public KaitaiStruct.ReadWrite _parent() { return _parent; }
public void set_parent(KaitaiStruct.ReadWrite _v) { _dirty = true; _parent = _v; }
}