7f3184a6c5
The check for the MacOS X version (10.7) is problematic, because it fails unless _DARWIN_C_SOURCE is defined if also _POSIX_C_SOURCE or _XOPEN_SOURCE is defined, as then the Darwin version defines are not defined. We cannot force _DARWIN_C_SOURCE reliably in the header either, because we cannot be sure that the libfdt_env.h has not already been included by another source before. The check is also only for very old versions of Mac OS X. In the interest of not replacing strnlen arbitrarily for sources using libfdt and considering that the last version of OS X 10.6 was released in 2011 I propose to remove the workaround for that system. We noticed as compiling fdt_strnlen in C++ environments fails (missing cast for memchr). Signed-off-by: Adam Lackorzynski <adam@l4re.org> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Device Tree Compiler and libfdt
The source tree contains the Device Tree Compiler (dtc) toolchain for working with device tree source and binary files and also libfdt, a utility library for reading and manipulating the binary format.
dtc and libfdt are maintained by:
Python library
A Python library wrapping libfdt is also available. To build this you
will need to install swig and Python development files. On Debian
distributions:
$ sudo apt-get install swig python3-dev
The library provides an Fdt class which you can use like this:
$ PYTHONPATH=../pylibfdt python3
>>> import libfdt
>>> fdt = libfdt.Fdt(open('test_tree1.dtb', mode='rb').read())
>>> node = fdt.path_offset('/subnode@1')
>>> print(node)
124
>>> prop_offset = fdt.first_property_offset(node)
>>> prop = fdt.get_property_by_offset(prop_offset)
>>> print('%s=%s' % (prop.name, prop.as_str()))
compatible=subnode1
>>> node2 = fdt.path_offset('/')
>>> print(fdt.getprop(node2, 'compatible').as_str())
test_tree1
You will find tests in tests/pylibfdt_tests.py showing how to use each
method. Help is available using the Python help command, e.g.:
$ cd pylibfdt
$ python3 -c "import libfdt; help(libfdt)"
If you add new features, please check code coverage:
$ sudo apt-get install python3-coverage
$ cd tests
# It's just 'coverage' on most other distributions
$ python3-coverage run pylibfdt_tests.py
$ python3-coverage html
# Open 'htmlcov/index.html' in your browser
The library can be installed with pip from a local source tree:
$ pip install . [--user|--prefix=/path/to/install_dir]
Or directly from a remote git repo:
$ pip install git+git://git.kernel.org/pub/scm/utils/dtc/dtc.git@main
The install depends on libfdt shared library being installed on the
host system first. Generally, using --user or --prefix is not
necessary and pip will use the default location for the Python
installation which varies if the user is root or not.
You can also install everything via make if you like, but pip is recommended.
To install both libfdt and pylibfdt you can use:
$ make install [PREFIX=/path/to/install_dir]
To disable building the python library, even if swig and Python are available, use:
$ make NO_PYTHON=1
More work remains to support all of libfdt, including access to numeric values.
Mailing lists
- The devicetree-compiler list is for discussion about dtc and libfdt implementation.
- Core device tree bindings are discussed on the devicetree-spec list.