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be used on the host system (and not installed on the device, if required). The GPL'd one is still available if there are any devices that need it (make universe passes with it, including kernels that use fdt, but there may be some out-of-tree ones). WITH_GPL_DTC can be used to select the old one, for now. Probably won't be MFC'd, but we'll remove the GPL'd version in head after the new one has had a lot more testing and ship it in 10.0.
66 lines
2.5 KiB
Plaintext
66 lines
2.5 KiB
Plaintext
$FreeBSD$
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Notes for people hacking on dtc
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===============================
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This file contains some notes for people wishing to hack on dtc.
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Upstreaming
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-----------
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This code is developed in the FreeBSD svn repository:
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https://svn.freebsd.org/base/head/usr.bin/dtc
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If you got the source from anywhere else and wish to make changes, please
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ensure that you are working against the latest version, or you may end up
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fixing bugs that are already fixed upstream. Although the license makes no
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requirement that you share any improvements that you make, patches are very
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welcome.
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C++11
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-----
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This project currently aims to compile with g++ 4.2.1 and so doesn't make any
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use of C++11 features. It would be a good idea to relax this restriction once
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clang is the default compiler for ARM, MIPS and PowerPC.
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This code makes use of a lot of iterator loops, which would be cleaner using
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the new syntax in C++11. It also explicitly deletes a lot of objects held in
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collections in destructors that have these collections as their members. This
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could be simplified by using `shared_ptr`.
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The code does make use of `static_assert()`, but uses a macro in utility.hh to
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remove these if they are not supported. The FreeBSD standard headers also
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define a compatibility macro the implements static asserts in terms of an array
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with 1 element on success and -1 elements on failure.
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Adding New Checks
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-----------------
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Currently, the biggest weakness of this version of the tool is that it lacks
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most of the semantic checkers that can be implemented by simply reading the
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ePAPR spec. The `checker` class provides a simple superclass for implementing
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these quite easily. There are also helper methods on `device_tree` for finding
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specific nodes, for checks that require some understanding of the structure of
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the tree.
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We should probably add a parent pointer to the `node` class for easily walking
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up the tree.
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Adding Direct C Output
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----------------------
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The FreeBSD build system currently uses dtc to generate a blob and then
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converts this to C source code. A new `output_writer` subclass could easily
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generate the C directly.
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Parser Improvements
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-------------------
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There are a few FIXME lines in the parser for some corner cases that are not
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currently used by FreeBSD. These are mainly related to labels in the middle of
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values. These can be fixed by creating a new `property_value` with the
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specified label, starting at the location of the label. Don't forget to remove
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the associated comments from the BUGS section of the man page if you fix this.
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