Re: [RFC PATCH v2 00/11] objtool/klp: DWARF-based cross-build symbol correlation

[Josh Poimboeuf <jpoimboe@kernel.org>]

On Wed, Nov 04, 2026 at 09:31:46PM +0800, Longjun Luo wrote:
> Responses to v1 Review (Guide)
> ------------------------------
> 
> Thanks to Josh for reviewing v1. v2 responds as follows:
> 
> 1. `CONFIG_DEBUG_INFO` and split/reduced DWARF: as suggested, `klp-build`
>    now requires `CONFIG_DEBUG_INFO` and uses Kbuild's debug flags
>    (Patch 6). Reduced and split DWARF are supported (Patch 5). See
>    "Compatibility Limits and Build Requirements".
> 
> 2. Repeated macro statics and the one-line test: building on the
>    referencing-function idea, unchanged-function references resolve
>    repeated statics (Patch 9). The tree-wide test reduces v1's
>    `no correlation` warnings from 682/764 to zero (GCC/Clang). See
>    "Evaluation and Performance Overhead".
> 
> 3. Upgrading `no correlation` to an error and explicit annotations:
>    following this direction, v2 rejects ambiguous data references and
>    allows verified new data (Patch 10). See Case D for the
>    state-inheritance boundary, its kernel-wide impact, and proposed
>    annotations.
> 
> 4. Referencing functions, ThinLTO naming flags, and Full LTO: in ELF, the
>    referencing function only approximates the defining scope, and
>    `STT_FILE` and `.llvm.<hash>` suffixes only approximate the defining
>    TU. Definition identity distinguishes inlined helpers' state and
>    survives LTO renaming and `STT_FILE` merging; see Cases A-B.
> 
> 5. Toolchain reliability and performance: v2 cross-checks DWARF against
>    ELF and measures checksum/diff costs, including a separate memory
>    prototype. See "Design Overview", "Evaluation and Performance
>    Overhead", and "Open Questions and Next Steps".
 
Going forward, please reply directly to the review comments (including
sashiko reviews), as threaded emails are much easier to follow/discuss
than a summary like the above.

-- 
Josh