Claude review: gpu: nova-core: export Rust symbols for dependent modules

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

**Status: Acceptable as a workaround, with a concern**

This generates `EXPORT_SYMBOL_GPL()` calls for all Rust global text symbols in `nova_core.o` by piping `nm` output through `awk`:

```makefile
rust_exports = \
	$(NM) -p --defined-only $(1) | \
	awk '$$2 == "T" && $$3 ~ /^_R/ { \
		printf "extern void %s(void); EXPORT_SYMBOL_GPL(%s);\n", $$3, $$3 \
	}'
```

The filter is correct: Rust v0 mangled symbols start with `_R`, and checking `$$2 == "T"` restricts to global text symbols. The generated `extern void fn(void)` declarations are technically mistyped, but since only `EXPORT_SYMBOL_GPL()` uses them (no C code actually calls them with this signature), this is harmless.

**Concern: over-exporting.** This exports *every* Rust text symbol from nova-core, not just the ones nova-drm actually needs. This means internal implementation details, monomorphized generics, trait method implementations, etc. all become part of the module's exported API. While acceptable as a temporary workaround, this could interact poorly with symbol versioning or module loading if any internal symbols change. A more targeted approach (e.g., an explicit symbol list) would be cleaner but harder to maintain as a workaround.

The module composite object rename from `nova_core.o` → `nova-core.o` with `nova-core-y := nova_core.o nova_core_exports.o` is clean and follows standard Kbuild patterns.

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Generated by Claude Code Patch Reviewer