Cross-build of rust 1.91.0 fails for powerpc-unknown-netbsd with linker errors

[he32]

Summary

The cross-build for the powerpc-unknown-netbsd target fails during the build of

Building stage2 rust-analyzer (stage1:x86_64-unknown-netbsd -> stage2:powerpc-unknown-netbsd)

so at the very end of the build. The failure is:

          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: /u/macppc/dest/usr/lib/crt0.o: in function `__start':
          (.text+0x120): relocation truncated to fit: R_PPC_PLTREL24 against symbol `abort' defined in .text section in /u/macppc/dest/lib/libc.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: /u/macppc/dest/usr/lib/crt0.o: in function `___start':
          (.text+0x1bc): relocation truncated to fit: R_PPC_PLTREL24 against symbol `atexit' defined in .text section in /u/macppc/dest/lib/libc.so+8000

and many, many more similar ones.
This apparently indicates that the attempted-to-be-linked program has bloated beyond 32MB.

Command used

python3.12 ./x.py dist -j 40

with lots of environment variable tweaks for cross compilation.

Expected behaviour

I expected the build to complete without error.

Actual behaviour

See above. Some parts of the code which wants to call each other gets displaced more than 32MB apart, so the code can no longer safely use the PC-relative R_PPC_PLTREL24 relocation type (which apparently refers to 32-bit words, since 2^24 is 16M).

Bootstrap configuration (bootstrap.toml)

(empty here)

An updated bootstrap.toml can be uploaded if needed later (I'm currently building for another target...)

Operating system

Host OS: NetBSD/amd64 10.1

HEAD

castor: {11} echo `cat work/rustc-1.91.0-src/git-commit-hash `
f8297e351a40c1439a467bbbb6879088047f50b3
castor: {12} 

I.e. extracted from the 1.91.0 tarball.

Discussion

I know that on PowerPC, gcc has the additional options -mlongcall, and depending on linker and gcc version, -no-pltseq may then also be required. I will try to see if I can direct the cross-build to use these options.

However, I would like some hints how I can direct the rust compiler to do similarly for the code it generates.

Additional context

Build Log

Some more parts of the build log (still incomplete):

          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: /u/macppc/dest/usr/lib/crt0.o: in function `__start':
          (.text+0x120): relocation truncated to fit: R_PPC_PLTREL24 against symbol `abort' defined in .text section in /u/macppc/dest/lib/libc.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: /u/macppc/dest/usr/lib/crt0.o: in function `___start':
          (.text+0x1bc): relocation truncated to fit: R_PPC_PLTREL24 against symbol `atexit' defined in .text section in /u/macppc/dest/lib/libc.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: (.text+0x1c0): relocation truncated to fit: R_PPC_PLTREL24 against symbol `_libc_init' defined in .text section in /u/macppc/dest/lib/libc.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: (.text+0x1fc): relocation truncated to fit: R_PPC_PLTREL24 against symbol `atexit' defined in .text section in /u/macppc/dest/lib/libc.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: (.text+0x22c): relocation truncated to fit: R_PPC_PLTREL24 against symbol `atexit' defined in .text section in /u/macppc/dest/lib/libc.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: (.text+0x244): relocation truncated to fit: R_PPC_PLTREL24 against symbol `exit' defined in .text section in /u/macppc/dest/lib/libc.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: (.text+0x270): relocation truncated to fit: R_PPC_PLTREL24 against symbol `__syscall' defined in .text section in /u/macppc/dest/lib/libc.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: (.text+0x278): relocation truncated to fit: R_PPC_PLTREL24 against symbol `_exit' defined in .text section in /u/macppc/dest/lib/libc.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/build/x86_64-unknown-netbsd/stage2-tools/powerpc-unknown-netbsd/release/deps/rust_analyzer-26adb153f4b9bf2a.rust_analyzer.4917a4ff91af159c-cgu.03.rcgu.o: in function `_RNvMs4_NtCsdJJMeYLMKtb_12sharded_slab4pageINtB5_6SharedNtNtNtCs3uf4daDK168_18tracing_subscriber8registry7sharded9DataInnerNtNtB7_3cfg13DefaultConfigE8allocateCs6h4gWHgiW4G_13rust_analyzer':
          rust_analyzer.4917a4ff91af159c-cgu.03:(.text.unlikely._RNvMs4_NtCsdJJMeYLMKtb_12sharded_slab4pageINtB5_6SharedNtNtNtCs3uf4daDK168_18tracing_subscriber8registry7sharded9DataInnerNtNtB7_3cfg13DefaultConfigE8allocateCs6h4gWHgiW4G_13rust_analyzer+0x7c): relocation truncated to fit: R_PPC_PLTREL24 against symbol `alloc::raw_vec::handle_error' defined in .text section in /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/build/x86_64-unknown-netbsd/stage1/lib/rustlib/powerpc-unknown-netbsd/lib/librustc_driver-0b5acf8e509b6fda.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: rust_analyzer.4917a4ff91af159c-cgu.03:(.text.unlikely._RNvMs4_NtCsdJJMeYLMKtb_12sharded_slab4pageINtB5_6SharedNtNtNtCs3uf4daDK168_18tracing_subscriber8registry7sharded9DataInnerNtNtB7_3cfg13DefaultConfigE8allocateCs6h4gWHgiW4G_13rust_analyzer+0x8c): relocation truncated to fit: R_PPC_PLTREL24 against symbol `_RNvCsg3D0vmXOPdo_7___rustc35___rust_no_alloc_shim_is_unstable_v2' defined in .text section in /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/build/x86_64-unknown-netbsd/stage1/lib/rustlib/powerpc-unknown-netbsd/lib/librustc_driver-0b5acf8e509b6fda.so+8000
          /u/macppc/tools/bin/../lib/gcc/powerpc--netbsd/7.4.0/../../../../powerpc--netbsd/bin/ld: rust_analyzer.4917a4ff91af159c-cgu.03:(.text.unlikely._RNvMs4_NtCsdJJMeYLMKtb_12sharded_slab4pageINtB5_6SharedNtNtNtCs3uf4daDK168_18tracing_subscriber8registry7sharded9DataInnerNtNtB7_3cfg13DefaultConfigE8allocateCs6h4gWHgiW4G_13rust_analyzer+0x9c): relocation truncated to fit: R_PPC_PLTREL24 against symbol `_RNvCsg3D0vmXOPdo_7___rustc12___rust_alloc' defined in .text section in /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/build/x86_64-unknown-netbsd/stage1/lib/rustlib/powerpc-unknown-netbsd/lib/librustc_driver-0b5acf8e509b6fda.so+8000

[he32]

Hmm... I know it may pain others, but ... is rust-analyzer an essential part of the rust compiler distribution? Said another way: is there a way to make the build of rust-analyzer optional, and disable it for this particular target?

And ... looking a bit closer at the above error messages, it is evident that the system-provided startup code in crt0.o gets placed too far apart from libc.so to be able to use the R_PPC_PLTREL24 relocation type which is used in crt0.o. And this cannot be simply fixed by adding -mlongcall to the gcc invocations in the rust build -- it would require a system rebuild with that option applied to certain object file builds.

That said, still, I'm still hoping someone can tell me how to sneak in -mlongcall or whatever is corresponding to that and use if to direct the rust code generator to do the similar thing. Anyone able to supply that clue?

[mati865]

You can build without rust-analyzer as a part of extended build by manually specifying the list of tools without it:

rust/bootstrap.example.toml

Lines 379 to 390 in 843f8ce

	#build.tools = [
	# "cargo",
	# "clippy",
	# "rustdoc",
	# "rustfmt",
	# "rust-analyzer",
	# "rust-analyzer-proc-macro-srv",
	# "analysis",
	# "src",
	# "wasm-component-ld",
	# "miri", "cargo-miri" # for dev/nightly channels
	#]

[he32]

Thanks! Following that lead.