Add ability to resolve symbols pointing to phandles instead of strings.
Combining this with existing fixups infrastructure allows creating
symbols in overlays that refer to undefined phandles. This is planned to
be used for addon board chaining [1].
Patch 2 containing tests demonstrates how this looks in practice.
Open Items:
1. Phandle vs String identification:
I am not sure how to distinguish between symbols that are paths and
phandles. Currently I am checking the proplen and if the first byte
is '/'. However, this can cause problems if the number of phandles in
dt exceed 0x2f000000 or 788,529,152.
Alternatively, if we can be sure that there will be no node whose
path is of length = 4, i.e. a node name of 2 characters ('\' and NULL
already take up 2 characters), we can avoid the '/' check.
[1]: https://lore.kernel.org/linux-arm-kernel/20240702164403.29067-1-afd@xxxxxx/
Signed-off-by: Ayush Singh <ayush@xxxxxxxxxxxxxxx>
---
Ayush Singh (2):
libfdt: overlay: Allow resolving phandle symbols
tests: Add test for symbol resolution
libfdt/fdt_overlay.c | 16 ++++++++++------
tests/overlay_overlay_symbols1.dts | 12 ++++++++++++
tests/overlay_overlay_symbols2.dts | 9 +++++++++
tests/overlay_overlay_symbols_user.dts | 26 ++++++++++++++++++++++++++
tests/run_tests.sh | 19 +++++++++++++++++++
5 files changed, 76 insertions(+), 6 deletions(-)
---
base-commit: 99031e3a4a6e479466ae795790b44727434ca27d
change-id: 20240829-symbol-phandle-9d1e0489c32a
Best regards,
--
Ayush Singh <ayush@xxxxxxxxxxxxxxx>
