checks: Add missing phandle_references prereq to interrupts_property The WARNING macro signature is (name, fn, data, ...prereqs), but interrupts_property was registered with &phandle_references in the data slot instead of as a prereq. Since c->data is const void *, the misuse compiled silently and the check has been running with num_prereqs == 0. The bug is normally masked: many other checks (interrupt_map, gpios_property, omit_unused_nodes, and the *_property checks generated by WARNING_PROPERTY_PHANDLE_CELLS) correctly list phandle_references as a prereq, and run_check recurses into prereqs unconditionally. As long as any one of them is enabled, fixup_phandle_references is pulled in transitively and the parser's 0xffffffff placeholder is replaced with the real phandle before check_interrupts_property reads it. The bug becomes visible when every other consumer of phandle_references is silenced (-Eno-phandle_references plus -Wno- for the *_property, gpios_property and interrupt_map checks). In that case the placeholder remains and interrupts_property falsely reports "Invalid phandle" / "Missing interrupt-parent" on a valid tree. Reordering check_table[] could also expose it under default flags. Add the missing NULL so &phandle_references lands in the prereq slot. Signed-off-by: Aristo Chen <aristo.chen@canonical.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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:
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.