Also referred to as Devicetree Blob (DTB). It is a flat binary encoding of data (primarily devicetree data, although other data is possible as well). The data is internally stored as a tree of named nodes and properties. Nodes contain properties and child nodes, while properties are name-value pairs.
The Devicetree Blobs (.dtb files) are compiled from the Devicetree Source
files (.dts) through the Devicetree compiler (DTC).
On Linux systems that support this, the blobs can be accessed in
/sys/firmware/fdt:
The encoding of strings used in the strings_block and structure_block is
actually a subset of ASCII:
https://devicetree-specification.readthedocs.io/en/v0.3/devicetree-basics.html#node-names
Example files:
This page hosts a formal specification of Flattened Devicetree Format 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 = Dtb.from_file("path/to/local/file.dtb")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = Dtb(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.magic # => get magic
# 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
from enum import Enum
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 Dtb(KaitaiStruct):
"""Also referred to as Devicetree Blob (DTB). It is a flat binary encoding
of data (primarily devicetree data, although other data is possible as well).
The data is internally stored as a tree of named nodes and properties. Nodes
contain properties and child nodes, while properties are name-value pairs.
The Devicetree Blobs (`.dtb` files) are compiled from the Devicetree Source
files (`.dts`) through the Devicetree compiler (DTC).
On Linux systems that support this, the blobs can be accessed in
`/sys/firmware/fdt`:
* <https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-firmware-ofw>
The encoding of strings used in the `strings_block` and `structure_block` is
actually a subset of ASCII:
<https://devicetree-specification.readthedocs.io/en/v0.3/devicetree-basics.html#node-names>
Example files:
* <https://github.com/qemu/qemu/tree/master/pc-bios>
.. seealso::
Source - https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html
.. seealso::
Source - https://elinux.org/images/f/f4/Elc2013_Fernandes.pdf
"""
class Fdt(Enum):
begin_node = 1
end_node = 2
prop = 3
nop = 4
end = 9
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"\xD0\x0D\xFE\xED":
raise kaitaistruct.ValidationNotEqualError(b"\xD0\x0D\xFE\xED", self.magic, self._io, u"/seq/0")
self.total_size = self._io.read_u4be()
self.ofs_structure_block = self._io.read_u4be()
self.ofs_strings_block = self._io.read_u4be()
self.ofs_memory_reservation_block = self._io.read_u4be()
self.version = self._io.read_u4be()
self.min_compatible_version = self._io.read_u4be()
if not self.min_compatible_version <= self.version:
raise kaitaistruct.ValidationGreaterThanError(self.version, self.min_compatible_version, self._io, u"/seq/6")
self.boot_cpuid_phys = self._io.read_u4be()
self.len_strings_block = self._io.read_u4be()
self.len_structure_block = self._io.read_u4be()
class MemoryBlock(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.entries = []
i = 0
while not self._io.is_eof():
self.entries.append(Dtb.MemoryBlockEntry(self._io, self, self._root))
i += 1
class FdtBlock(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.nodes = []
i = 0
while True:
_ = Dtb.FdtNode(self._io, self, self._root)
self.nodes.append(_)
if _.type == Dtb.Fdt.end:
break
i += 1
class MemoryBlockEntry(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.address = self._io.read_u8be()
self.size = self._io.read_u8be()
class Strings(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.strings = []
i = 0
while not self._io.is_eof():
self.strings.append((self._io.read_bytes_term(0, False, True, True)).decode(u"ASCII"))
i += 1
class FdtProp(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.len_property = self._io.read_u4be()
self.ofs_name = self._io.read_u4be()
self.property = self._io.read_bytes(self.len_property)
self.padding = self._io.read_bytes((-(self._io.pos()) % 4))
@property
def name(self):
if hasattr(self, '_m_name'):
return self._m_name
io = self._root.strings_block._io
_pos = io.pos()
io.seek(self.ofs_name)
self._m_name = (io.read_bytes_term(0, False, True, True)).decode(u"ASCII")
io.seek(_pos)
return getattr(self, '_m_name', None)
class FdtNode(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.type = KaitaiStream.resolve_enum(Dtb.Fdt, self._io.read_u4be())
_on = self.type
if _on == Dtb.Fdt.begin_node:
self.body = Dtb.FdtBeginNode(self._io, self, self._root)
elif _on == Dtb.Fdt.prop:
self.body = Dtb.FdtProp(self._io, self, self._root)
class FdtBeginNode(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 = (self._io.read_bytes_term(0, False, True, True)).decode(u"ASCII")
self.padding = self._io.read_bytes((-(self._io.pos()) % 4))
@property
def memory_reservation_block(self):
if hasattr(self, '_m_memory_reservation_block'):
return self._m_memory_reservation_block
_pos = self._io.pos()
self._io.seek(self.ofs_memory_reservation_block)
self._raw__m_memory_reservation_block = self._io.read_bytes((self.ofs_structure_block - self.ofs_memory_reservation_block))
_io__raw__m_memory_reservation_block = KaitaiStream(BytesIO(self._raw__m_memory_reservation_block))
self._m_memory_reservation_block = Dtb.MemoryBlock(_io__raw__m_memory_reservation_block, self, self._root)
self._io.seek(_pos)
return getattr(self, '_m_memory_reservation_block', None)
@property
def structure_block(self):
if hasattr(self, '_m_structure_block'):
return self._m_structure_block
_pos = self._io.pos()
self._io.seek(self.ofs_structure_block)
self._raw__m_structure_block = self._io.read_bytes(self.len_structure_block)
_io__raw__m_structure_block = KaitaiStream(BytesIO(self._raw__m_structure_block))
self._m_structure_block = Dtb.FdtBlock(_io__raw__m_structure_block, self, self._root)
self._io.seek(_pos)
return getattr(self, '_m_structure_block', None)
@property
def strings_block(self):
if hasattr(self, '_m_strings_block'):
return self._m_strings_block
_pos = self._io.pos()
self._io.seek(self.ofs_strings_block)
self._raw__m_strings_block = self._io.read_bytes(self.len_strings_block)
_io__raw__m_strings_block = KaitaiStream(BytesIO(self._raw__m_strings_block))
self._m_strings_block = Dtb.Strings(_io__raw__m_strings_block, self, self._root)
self._io.seek(_pos)
return getattr(self, '_m_strings_block', None)