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NobodyXu opened this issue Oct 8, 2022 · 8 comments
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cross 0.2.4 failed to compile libz-ng-sys v1.1.8 on armv7-unknown-linux-gnueabihf #1066

NobodyXu opened this issue Oct 8, 2022 · 8 comments
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A-arm Area: ARM targets invalid upstream

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@NobodyXu
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NobodyXu commented Oct 8, 2022 •
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Describe your issue

Running cmd

cross build --target armv7-unknown-linux-gnueabihf --profile release --no-default-features --features zlib-ng,static,rustls,trust-dns,fancy-no-backtrace,log_release_max_level_debug -Z build-std=std,panic_abort -Z build-std-features=panic_immediate_abort

on cargo-binstall v0.15.0 failed with error:

  /usr/lib/gcc-cross/arm-linux-gnueabihf/5/include/arm_neon.h:31:2: error: #error You must enable NEON instructions (e.g. -mfloat-abi=softfp -mfpu=neon) to use arm_neon.h
   #error You must enable NEON instructions (e.g. -mfloat-abi=softfp -mfpu=neon) to use arm_neon.h

From CI failure.

and

  In file included from /cargo/registry/src/index.crates.io-e139d0d48fed7772/libz-ng-sys-1.1.8/src/zlib-ng/compare256.c:7:0:
  /cargo/registry/src/index.crates.io-e139d0d48fed7772/libz-ng-sys-1.1.8/src/zlib-ng/fallback_builtins.h:102:15: error: unknown type name 'uint16x8x4_t'
   static inline uint16x8x4_t vld1q_u16_x4(uint16_t *a) {

This might be related to #733 and #985
I've tried setting export RUSTFLAGS="-C link-arg=-lgcc -Clink-arg=-static-libgcc" according to https://github.com/cross-rs/cross/wiki/FAQ#undefined-reference-with-build-std but still doesn't work.

Compiling libz-ng-sys worked before #1046

What target(s) are you cross-compiling for?

armv7-unknown-linux-gnueabihf

Which operating system is the host (e.g computer cross is on) running?

  • macOS
  • Windows
  • Linux / BSD
  • other OS (specify in description)

What architecture is the host?

  • x86_64 / AMD64
  • arm32
  • arm64 (including Mac M1)

What container engine is cross using?

  • docker
  • podman
  • other container engine (specify in description)

cross version

cross 0.2.4

Example

No response

Additional information / notes

No response
This was referenced Oct 8, 2022
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@Alexhuszagh
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Alexhuszagh commented Oct 8, 2022 •
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This isn't a cross bug: it's an issue with the library you're trying to use: ARMv7HF defaults to using VFPv3, not NEON, and refuses to compile NEON intrinsics unless you basically force it to. You'd have to add -C target-feature=+neon to RUSTFLAGS, and even then I doubt it would work. If you want an ARMv7 hard-float target that supports NEON by default, use thumbv7neon-unknown-linux-gnueabihf. FYI: your library is also asking you to use -mfloat-abi=softfp which is definitely wrong here: it would have to be -mfloat-abi=hard.

There's something wrong with the libraries you are using, not with the toolchain itself.

@Alexhuszagh Alexhuszagh added invalid A-arm Area: ARM targets labels Oct 8, 2022
This was referenced Oct 8, 2022
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@Alexhuszagh
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Let me know if this fails to compile with NEON intrinsics available, in which case, there might be a bug in the toolchain. But right now, this error definitely does not seem to be an issue in cross, especially considering our toolchain is direct from Ubuntu's repositories.

@NobodyXu
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NobodyXu commented Oct 8, 2022

Running

export RUSTFLAGS="-C link-arg=-lgcc -Clink-arg=-static-libgcc -C target-feature=+neon"

cross +nightly build --target armv7-unknown-linux-gnueabihf --profile release --no-default-features --features zlib-ng,static,rustls,trust-dns,fancy-no-backtrace,log_release_max_level_debug -Z build-std=std,panic_abort -Z build-std-features=panic_immediate_abort

still failed with the neon error.

@Alexhuszagh
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Alexhuszagh commented Oct 8, 2022 •
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Interesting. I still doubt this is a toolchain error since using the C++ toolchain itself works as expected:

$ docker run -it --rm ghcr.io/cross-rs/armv7-unknown-linux-gnueabihf:0.2.4 bash
$ echo '#include <iostream>

int main() {
    std::cout << "Hello World" << std::endl;
}' >> main.cc

$ arm-linux-gnueabihf-g++  main.cc -march=armv7-a -mfpu=neon-vfpv4
$ readelf -A a.out
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "7-A"
  Tag_CPU_arch: v7
  Tag_CPU_arch_profile: Application
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-2
  Tag_FP_arch: VFPv4
  Tag_Advanced_SIMD_arch: NEONv1 with Fused-MAC
  Tag_ABI_PCS_wchar_t: 4
  Tag_ABI_FP_rounding: Needed
  Tag_ABI_FP_denormal: Needed
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte
  Tag_ABI_align_preserved: 8-byte, except leaf SP
  Tag_ABI_enum_size: int
  Tag_ABI_VFP_args: VFP registers
  Tag_CPU_unaligned_access: v6

$ arm-linux-gnueabihf-g++  main.cc -march=armv7-a -mfpu=neon
$  readelf -A a.out
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "7-A"
  Tag_CPU_arch: v7
  Tag_CPU_arch_profile: Application
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-2
  Tag_FP_arch: VFPv3
  Tag_Advanced_SIMD_arch: NEONv1
  Tag_ABI_PCS_wchar_t: 4
  Tag_ABI_FP_rounding: Needed
  Tag_ABI_FP_denormal: Needed
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte
  Tag_ABI_align_preserved: 8-byte, except leaf SP
  Tag_ABI_enum_size: int
  Tag_ABI_VFP_args: VFP registers
  Tag_CPU_unaligned_access: v6

IE, it supports NEONv1, VFPv3, and VFPv4, as expected. Also, just testing it with a Rust package, this also works as expected (ensuring that these are the features enabled by default, not optional ones):

$ cross build --target armv7-unknown-linux-gnueabihf -v
$  readelf -A target/armv7-unknown-linux-gnueabihf/debug/hello2
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "7-A"
  Tag_CPU_arch: v7
  Tag_CPU_arch_profile: Application
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-2
  Tag_FP_arch: VFPv3-D16
  Tag_ABI_PCS_GOT_use: GOT-indirect
  Tag_ABI_PCS_wchar_t: 4
  Tag_ABI_FP_rounding: Needed
  Tag_ABI_FP_denormal: Needed
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte
  Tag_ABI_enum_size: int
  Tag_ABI_VFP_args: VFP registers
  Tag_CPU_unaligned_access: v6
  Tag_ABI_FP_16bit_format: IEEE 754

$ RUSTFLAGS="-C target-feature=+neon" cross build --target armv7-unknown-linux-gnueabihf -v
$  readelf -A target/armv7-unknown-linux-gnueabihf/debug/hello2
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "7-A"
  Tag_CPU_arch: v7
  Tag_CPU_arch_profile: Application
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-2
  Tag_FP_arch: VFPv3
  Tag_Advanced_SIMD_arch: NEONv1
  Tag_ABI_PCS_GOT_use: GOT-indirect
  Tag_ABI_PCS_wchar_t: 4
  Tag_ABI_FP_rounding: Needed
  Tag_ABI_FP_denormal: Needed
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte
  Tag_ABI_enum_size: int
  Tag_ABI_VFP_args: VFP registers
  Tag_CPU_unaligned_access: v6
  Tag_ABI_FP_16bit_format: IEEE 754

$  cross build --target thumbv7neon-unknown-linux-gnueabihf -vv
$ readelf -A target/thumbv7neon-unknown-linux-gnueabihf/debug/hello2
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "7-A"
  Tag_CPU_arch: v7
  Tag_CPU_arch_profile: Application
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-2
  Tag_FP_arch: VFPv4
  Tag_Advanced_SIMD_arch: NEONv1 with Fused-MAC
  Tag_ABI_PCS_GOT_use: GOT-indirect
  Tag_ABI_PCS_wchar_t: 4
  Tag_ABI_FP_rounding: Needed
  Tag_ABI_FP_denormal: Needed
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte
  Tag_ABI_enum_size: int
  Tag_ABI_VFP_args: VFP registers
  Tag_CPU_unaligned_access: v6
  Tag_ABI_FP_16bit_format: IEEE 754

So basically, everything works as expected here. NEON intrinsics are not enabled by default for armv7-unknown-linux-gnueabihf, but can be enabled, while they are for thumbv7neon-unknown-linux-gnueabihf.

@NobodyXu
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NobodyXu commented Oct 8, 2022

That makes me even more confused on what caused the issue here.
I will probably just disables libz-ng.

@Alexhuszagh
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Same result as #1067, using the latest main fixes this issue.

$ cross --version
cross 0.2.4 (0fcfc0b 2022-09-29)
$ cargo +nightly --version
cargo 1.66.0-nightly (0b84a35c2 2022-10-03)
cross +nightly build --target armv7-unknown-linux-gnueabihf --profile release --no-default-features --features zlib-ng,static,rustls,trust-dns,fancy-no-backtrace,log_release_max_level_debug -Z build-std=std,panic_abort -Z build-std-features=panic_immediate_abort

It seems like the move to GCC 9.4.0 and glibc 2.31 (from GCC 5.4.0 and 2.23) fixes the issue.

@Emilgardis
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Emilgardis commented Oct 8, 2022 •
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to fix this @NobodyXu , you can specify what image to build with, since we've fixed the direct backwards incompability with 0.2.4 and current main regarding env vars in #1047, you could specify

[package.metadata.cross.target.armv7-unknown-linux-gnueabihf]
image = "ghcr.io/cross-rs/armv7-unknown-linux-gnueabihf@sha256:45f953c4f4945a670cc0b7f2993f1581adbc60c900028ccfebdc421eef40f84a"

this comment also applies to #1067

instead of installing cross from main, use a pinned image with 0.2.4

@NobodyXu
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NobodyXu commented Oct 9, 2022

Thanks, but I would probably just wait for cross v0.3.0 since it is going to be ready soon.

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