dynamic-resolution-notes.rst 1.1 KB

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  1. .. SPDX-License-Identifier: GPL-2.0
  2. ==================================
  3. Device Tree Dynamic Resolver Notes
  4. ==================================
  5. This document describes the implementation of the in-kernel
  6. Device Tree resolver, residing in drivers/of/resolver.c
  7. How the resolver works
  8. ----------------------
  9. The resolver is given as an input an arbitrary tree compiled with the
  10. proper dtc option and having a /plugin/ tag. This generates the
  11. appropriate __fixups__ & __local_fixups__ nodes.
  12. In sequence the resolver works by the following steps:
  13. 1. Get the maximum device tree phandle value from the live tree + 1.
  14. 2. Adjust all the local phandles of the tree to resolve by that amount.
  15. 3. Using the __local__fixups__ node information adjust all local references
  16. by the same amount.
  17. 4. For each property in the __fixups__ node locate the node it references
  18. in the live tree. This is the label used to tag the node.
  19. 5. Retrieve the phandle of the target of the fixup.
  20. 6. For each fixup in the property locate the node:property:offset location
  21. and replace it with the phandle value.