arm-unknown-linux-gnueabihf produces armv7 output not armv6

[mkj]

I'm cross compiling on x64 Linux to a Raspberry Pi 1, Raspbian Jessie. Binaries produced by arm-unknown-linux-gnueabi target work fine, binaries from arm-unknown-linux-gnueabihf segfault in _start().

Readelf tells me that the arm-unknown-linux-gnueabihf target is actually armv7, which contradicts https://forge.rust-lang.org/platform-support.html

~/src/rusthello> readelf -A target/*/debug/rusthello 

File: target/arm-unknown-linux-gnueabi/debug/rusthello
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "ARM v6"
  Tag_CPU_arch: v6                                           <--
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-1
  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_CPU_unaligned_access: v6
  Tag_ABI_FP_16bit_format: IEEE 754

File: target/arm-unknown-linux-gnueabihf/debug/rusthello
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

File: target/armv7-unknown-linux-gnueabihf/debug/rusthello
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

rustc 1.14.0 (e8a012324 2016-12-16)
binary: rustc
commit-hash: e8a0123241f0d397d39cd18fcc4e5e7edde22730
commit-date: 2016-12-16
host: x86_64-unknown-linux-gnu
release: 1.14.0
LLVM version: 3.9

[japaric]

I think this may be your cross toolchain's fault because all the Rust side is v6, AFAICT:

$ readelf -A $(rustc --print sysroot)/lib/rustlib/arm-unknown-linux-gnueabihf/lib/*.rlib | grep Tag_CPU_arch
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
(..)

If you are using the gcc-arm-linux-gnueabihf package that ships with Ubuntu, that would be problem because that toolchain targets ARMv7.

$ readelf -A /usr/arm-linux-gnueabihf/lib/crt1.o
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_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

You should use the toolchain in the raspberrypi/tools repo or build your own but that targets v6.

[mkj]

Thank you @japaric , that is the problem. I was using the Ubuntu toolchain, the raspberrypi one works as expected.
Sorry for the noise.

[cubetastic33]

@japaric

I think this may be your cross toolchain's fault because all the Rust side is v6, AFAICT:

$ readelf -A $(rustc --print sysroot)/lib/rustlib/arm-unknown-linux-gnueabihf/lib/*.rlib | grep Tag_CPU_arch
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
  Tag_CPU_arch: v6
(..)

If you are using the gcc-arm-linux-gnueabihf package that ships with Ubuntu, that would be problem because that toolchain targets ARMv7.

$ readelf -A /usr/arm-linux-gnueabihf/lib/crt1.o
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_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

You should use the toolchain in the raspberrypi/tools repo or build your own but that targets v6.

I don't understand what to do. I do face a similar issue, I am trying to cross-compile to ARMv6 from Ubuntu. How am I supposed to do this?

[moriyas1984]

Any update?

I also need some directions to cross-compile to ARMv6 from Ubuntu.

Regards.

[moriyas1984]

Sorry, I have understood how to use it.

BurntSushi/ripgrep#676 (comment)

This comment told me how I should specify the linker in raspberrypi/tools.

Thank you.