Sami Tolvanen fdf302e6be gendwarfksyms: Skip files with no exports
Starting with Rust 1.91.0 (released 2025-10-30), in upstream commit
ab91a63d403b ("Ignore intrinsic calls in cross-crate-inlining cost model")
[1][2], `bindings.o` stops containing DWARF debug information because the
`Default` implementations contained `write_bytes()` calls which are now
ignored in that cost model (note that `CLIPPY=1` does not reproduce it).

This means `gendwarfksyms` complains:

      RUSTC L rust/bindings.o
    error: gendwarfksyms: process_module: dwarf_get_units failed: no debugging information?

There are several alternatives that would work here: conditionally
skipping in the cases needed (but that is subtle and brittle), forcing
DWARF generation with e.g. a dummy `static` (ugly and we may need to
do it in several crates), skipping the call to the tool in the Kbuild
command when there are no exports (fine) or teaching the tool to do so
itself (simple and clean).

Thus do the last one: don't attempt to process files if we have no symbol
versions to calculate.

  [ I used the commit log of my patch linked below since it explained the
    root issue and expanded it a bit more to summarize the alternatives.

      - Miguel ]

Cc: stable@vger.kernel.org # Needed in 6.17.y.
Reported-by: Haiyue Wang <haiyuewa@163.com>
Closes: https://lore.kernel.org/rust-for-linux/b8c1c73d-bf8b-4bf2-beb1-84ffdcd60547@163.com/
Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/CANiq72nKC5r24VHAp9oUPR1HVPqT+=0ab9N0w6GqTF-kJOeiSw@mail.gmail.com/
Link: ab91a63d40 [1]
Link: https://github.com/rust-lang/rust/pull/145910 [2]
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Haiyue Wang <haiyuewa@163.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20251110131913.1789896-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-11-11 20:37:11 +01:00
2025-02-19 14:53:27 -07:00
2025-11-09 15:10:19 -08:00
2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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