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David Gibson 8a88ad8bad dtc: Remove ugly include stack abuse
Currently, dt_from_source() uses push_input_file() to set up the
initial input file for the lexer.  That sounds sensible - put the
outermost input file at the bottom of the stack - until you realise
that what it *actually* does is pushes the current, uninitialized,
lexer input state onto the stack, then sets up the new lexer input.

That necessitates an extra check in pop_input_file(), rather than
signalling termination in the natural way when the include stack is
empty, it has to check when it pops the bogus uninitialized state off
the stack.  Ick.

With that fixed, push_input_file(), pop_input_file() and
incl_file_stack itself become local to the lexer, so make them static.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2008-03-23 08:00:33 -05:00
Documentation dtc: Whitespace cleanup 2007-09-18 09:43:26 -05:00
libfdt libfdt: Remove no longer used code from fdt_node_offset_by_compatible() 2008-02-18 08:29:01 -06:00
scripts Add DTC release version information. 2007-07-07 13:52:25 -05:00
tests dtc: Testcases for input handling 2008-03-23 08:00:33 -05:00
.gitignore Merge libfdt into dtc. 2007-06-14 15:05:55 +10:00
checks.c dtc: Strip redundant "name" properties 2008-03-23 08:00:33 -05:00
data.c dtc: Implement path references 2007-12-05 08:28:44 -06:00
dtc-lexer.l dtc: Remove ugly include stack abuse 2008-03-23 08:00:33 -05:00
dtc-parser.y dtc: Make eval_literal() static 2008-03-23 08:00:33 -05:00
dtc.c dtc: Make dtc_open_file() die() if unable to open requested file 2008-03-23 08:00:33 -05:00
dtc.h dtc: Make -I dtb mode use fill_fullpaths() 2008-03-23 08:00:33 -05:00
flattree.c dtc: Make -I dtb mode use fill_fullpaths() 2008-03-23 08:00:33 -05:00
fstree.c dtc: Make dtc_open_file() die() if unable to open requested file 2008-03-23 08:00:33 -05:00
ftdump.c dtc: Remove header information dumping 2008-01-03 07:46:29 -06:00
GPL dtc: Remove redundant copy of the GPL 2007-06-25 21:43:11 -05:00
livetree.c Return a non-zero exit code if an error occurs during dts parsing. 2008-01-04 08:21:54 -06:00
Makefile Tag Version 1.1.0 2008-01-24 10:16:07 -06:00
Makefile.dtc dtc: Move tree checking code to checks.c 2007-11-01 08:03:37 -05:00
README.license dtc/libfdt: Add README clarifying licensing 2008-01-04 08:37:36 -06:00
srcpos.c dtc: Make dtc_open_file() die() if unable to open requested file 2008-03-23 08:00:33 -05:00
srcpos.h dtc: Remove ugly include stack abuse 2008-03-23 08:00:33 -05:00
TODO dtc: Update TODO files 2007-12-19 08:20:26 -06:00
treesource.c dtc: Remove ugly include stack abuse 2008-03-23 08:00:33 -05:00

Licensing and contribution policy of dtc and libfdt
===================================================

This dtc package contains two pieces of software: dtc itself, and
libfdt which comprises the files in the libfdt/ subdirectory.  These
two pieces of software, although closely related, are quite distinct.
dtc does not incoporate or rely on libfdt for its operation, nor vice
versa.  It is important that these two pieces of software have
different license conditions.

As the copyright banners in each source file attest, dtc is licensed
under the GNU GPL.  The full text of the GPL can be found in the file
entitled 'GPL' which should be included in this package.  dtc code,
therefore, may not be incorporated into works which do not have a GPL
compatible license.

libfdt, however, is GPL/BSD dual-licensed.  That is, it may be used
either under the terms of the GPL, or under the terms of the 2-clause
BSD license (aka the ISC license).  The full terms of that license are
given in the copyright banners of each of the libfdt source files.
This is, in practice, equivalent to being BSD licensed, since the
terms of the BSD license are strictly more permissive than the GPL.

I made the decision to license libfdt in this way because I want to
encourage widespread and correct usage of flattened device trees,
including by proprietary or otherwise GPL-incompatible firmware or
tools.  Allowing libfdt to be used under the terms of the BSD license
makes that it easier for vendors or authors of such software to do so.

This does mean that libfdt code could be "stolen" - say, included in a
proprietary fimware and extended without contributing those extensions
back to the libfdt mainline.  While I hope that doesn't happen, I
believe the goal of allowing libfdt to be widely used is more
important than avoiding that.  libfdt is quite small, and hardly
rocket science; so the incentive for such impolite behaviour is small,
and the inconvenience caused therby is not dire.

Licenses such as the LGPL which would allow code to be used in non-GPL
software, but also require contributions to be returned were
considered.  However, libfdt is designed to be used in firmwares and
other environments with unusual technical constraints.  It's difficult
to anticipate all possible changes which might be needed to meld
libfdt into such environments and so difficult to suitably word a
license that puts the boundary between what is and isn't permitted in
the intended place.  Again, I judged encouraging widespread use of
libfdt by keeping the license terms simple and familiar to be the more
important goal.

**IMPORTANT** It's intended that all of libfdt as released remain
permissively licensed this way.  Therefore only contributions which
are released under these terms can be merged into the libfdt mainline.


David Gibson <david@gibson.dropbear.id.au>
(principal original author of dtc and libfdt)
2 November 2007