[PATCH v3 dwarves 0/2] pahole: add BTF layout encoding feature

A soon-to-arrive v9 series will add support to add BTF layout
information to BTF; this describes the BTF kinds known about at
time of encoding in order to support parsing even in cases where
the kinds are not known to the parser; the layout relates a
BTF kind to the amount of space it consumes via an optional single
element following the BTF type or a set of vlen-specified objects.

This series implements the support for the BTF "layout" feature
but does not require the libbpf changes to support it; the feature
test uses a weak declaration of btf__new_empty_opts() to handle the
unsupported case.

To test pahole with this feature, the following approach can be used;

1. Specify -DLIBBPF_EMBEDDED=OFF option to cmake
2. Install latest libbpf with associated patch series with layout support

Alternatively with embedded libbpf the changes can be applied to
the embedded libbpf in lib/bpf/src.

Changes since v2 [1]:

- Resynced, renamed kind_layout -> layout
- Avoid encoding layout info in split BTF since it is a waste of space

Changes since v1 [2]:

 - Resynced with latest pahole

[1] https://lore.kernel.org/dwarves/[email protected]/
[2] https://lore.kernel.org/dwarves/[email protected]/

Alan Maguire (2):
  pahole: Add "layout" BTF encoding feature
  man-pages: describe layout BTF feature

 btf_encoder.c      | 21 ++++++++++++++++++++-
 dwarves.h          |  4 ++++
 man-pages/pahole.1 |  2 ++
 pahole.c           |  6 ++++++
 4 files changed, 32 insertions(+), 1 deletion(-)

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2.39.3