On Tue, Apr 18, 2017 at 10:27:37AM -0600, Simon Glass wrote: > Hi Tom, > > On 18 April 2017 at 10:25, Tom Rini <tr...@konsulko.com> wrote: > > > > On Sun, Apr 16, 2017 at 08:22:14PM -0600, Simon Glass wrote: > > > > > Python libfdt bindings have recently been accepted upstream. While the > > > internals have changed a fair bit most of the API remains the same. Still, > > > a few functions are different from how they are used in U-Boot so changes > > > are needed to make this work. > > > > > > At present in U-Boot there are two libraries for accessing a device tree > > > file: > > > > > > - FdtNormal which uses U-Boot's own Python bindings > > > - FdtFallback which uses the fdtget command-line utility > > > > > > The latter is not a great solution: it is fairly slow since the DT is > > > re-read for every access and it cannot provide DT offsets or packing of > > > the DT. > > > > > > In addition, U-Boot now builds the libfdt module if swig is available, > > > meaning that the fallback module is not used in that case. > > > > > > Finally, at some point in the future distributions may start packaging the > > > libfdt Python module and it will be available without U-Boot needing to > > > build it itself. > > > > > > Therefore it seems like a good idea to take this opportunity to drop the > > > fallback module and just require that the Python libfdt bindings be > > > present (at least if need by the build). > > > > > > The bindings are needed in two situations: > > > - When dtoc is used to convert a device tree into C code. This is enabled > > > by CONFIG_SPL_OF_PLATDATA > > > - When binman is used to produce a firmware image. This is used on all x86 > > > and sunxi boards at present > > > > > > This series: > > > - Plumbs in building the Python libfdt module to the U-Boot build system > > > - Ensures that the module is always built if needed, print an error if > > > swig is not available (and thus the module cannot be built) > > > - Allows use of a libfdt.py module already installed on the machine > > > - Drops the FdtFallback support > > > - Moves fdt.h and libfdt.h into lib/libfdt to aid with syncing with > > > upstream, building the Python bindings and to keep the code together > > > - Merges Fdt and FdtNormal to simplify the code > > > - Adjusts the Fdt library to work with the new libfdt module > > > - Adds a few more tests to check access to properties in the DT > > > - Adjusts binman and dtoc to work with the new approach > > > > > > It should be possible to easily sync libfdt's Python bindings with U-Boot > > > in the future, as development there proceeds. > > > > While this came in late, my gut feeling is that it would be best to have > > this change in the next release (so that various upstreams can get used > > to the idea of basically always needing python installed to build). > > I'm a little worried that it might cause problems. I made it so that > it only *requires* python if is it actually needed, though it always > builds libfdt.py if it can. Or perhaps that is what you are saying, > that the only way to flush out upstream issues is to apply it?
What I'm saying is that distros (Fedora, openSUSE, OpenEmbedded) are going to make a blanket change (if they haven't already) to say that building U-Boot requires python to be installed (since they aren't likely to try and optimize it on a board-by-board basis when it's "easy" to just say it's an always dependency). If you think there's risk with the change itself, we can wait a release, that's fine too. Thanks! -- Tom
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