milenkovicm commented on issue #2043:
URL:
https://github.com/apache/datafusion-ballista/issues/2043#issuecomment-4996956681
This is a linker warning from Apple's `ld` (specifically the newer `ld`
shipped with recent Xcode/Command Line Tools, sometimes called `ld-prime` or
the "new linker"), not an error — your build still succeeds.
**What it means**
- `__eh_frame` is the ELF/Mach-O section that stores stack-unwinding
metadata: the information the runtime uses to walk the stack and run
destructors/cleanup when a panic or C++-style exception propagates.
- Rust generates this unwinding info for every function that could be
unwound through (relevant when `panic = "unwind"`, which is the default), and
with a large binary — like `ballista-executor`, which likely statically links a
huge dependency graph (Arrow, DataFusion, Tonic/gRPC, etc.) — this section can
grow very large.
- Apple's linker builds a **compact unwind table**, a more efficient
macOS-specific format that summarizes unwind info for fast lookup during
exception handling. It tries to encode `__eh_frame` entries as *offsets* into
this compact table.
- Those offsets have a fixed bit width, and if `__eh_frame` exceeds 16MB,
some entries can't be represented in the compact table anymore. The linker just
warns you and falls back to slower unwinding paths for the frames it couldn't
compact.
**Practical impact**
- Almost none for most programs. It only affects the speed of unwinding
(i.e., panics/exceptions), not normal execution speed.
- Since Rust binaries mostly `panic = "abort"` in release builds or rarely
unwind in hot paths, you're unlikely to notice anything.
**If you want to silence/avoid it**
- Set `panic = "abort"` in your release profile (in `Cargo.toml`):
```toml
[profile.release]
panic = "abort"
```
This removes unwind tables almost entirely, but means panics can no longer
be caught (`catch_unwind` won't work) — fine for most server binaries, but
check if anything in your stack relies on catching panics.
- Strip debug info / reduce codegen units, which can shrink the section
somewhat, though this is less reliable for actually fixing it.
- Otherwise, it's generally safe to just ignore this warning — it's
cosmetic/informational for large Rust binaries on modern macOS toolchains, and
you'll see it on many big Rust projects (this is a known, common warning in the
Rust community with big crates like DataFusion/Arrow-based binaries).
(LLM generated)
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