
On Tue, Apr 18, 2017 at 10:48:07AM -0600, Simon Glass wrote:
Hi Tom,
On 18 April 2017 at 10:33, Tom Rini trini@konsulko.com wrote:
On Tue, Apr 18, 2017 at 10:27:37AM -0600, Simon Glass wrote:
Hi Tom,
On 18 April 2017 at 10:25, Tom Rini trini@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!
I see. I'm not sure what is best. I checked for build errors and added some more tests so I'm fairly confident. But it is late (sorry, it was more work than I expected). I'll leave this up to you.
Alright, lets just have this queued up for early next window.