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

[Jiri Olsa <olsajiri@gmail.com>]

On Thu, Feb 26, 2026 at 08:52:38AM +0000, Alan Maguire wrote:
> 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/20251210202752.813919-1-alan.maguire@oracle.com/
> [2] https://lore.kernel.org/dwarves/20250528095349.788793-1-alan.maguire@oracle.com/
> 
> Alan Maguire (2):
>   pahole: Add "layout" BTF encoding feature
>   man-pages: describe layout BTF feature

lgtm

Acked-by: Jiri Olsa <jolsa@kernel.org>

jirka

> 
>  btf_encoder.c      | 21 ++++++++++++++++++++-
>  dwarves.h          |  4 ++++
>  man-pages/pahole.1 |  2 ++
>  pahole.c           |  6 ++++++
>  4 files changed, 32 insertions(+), 1 deletion(-)
> 
> -- 
> 2.39.3
>