armv7r_none_eabihf.rs

// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// Targets the Cortex-R4F/R5F processor (ARMv7-R, little-endian)

use std::default::Default;
use spec::{LinkerFlavor, PanicStrategy, Target, TargetOptions, TargetResult};

pub fn target() -> TargetResult {
    Ok(Target {
        llvm_target: "armv7r-none-eabihf".to_string(),
        target_endian: "little".to_string(),
        target_pointer_width: "32".to_string(),
        target_c_int_width: "32".to_string(),
        data_layout: "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
        arch: "arm".to_string(),
        target_os: "none".to_string(),
        target_env: "".to_string(),
        target_vendor: "".to_string(),
        linker_flavor: LinkerFlavor::Gcc,

        options: TargetOptions {
            executables: true,
            relocation_model: "static".to_string(),
            panic_strategy: PanicStrategy::Abort,
            features: "+v7,+armv7-r,+db,+dsp,+dsp,+hwdiv,+rclass,+r5,+ras,+vfp3,+d16,+slow-fp-brcc,+hwdiv-arm,+slowfpvmlx,+thumb2".to_string(),
            max_atomic_width: Some(32),
            abi_blacklist: super::arm_base::abi_blacklist(),
            emit_debug_gdb_scripts: false,
            .. Default::default()
        },
    })
}

build.log

<...elided...>

running: "arm-eabi-gcc" "-O2" "-ffunction-sections" "-fdata-sections" "-fPIC" "-ffunction-sections" "-fdata-sections" "-fPIC" "-march=armv7-r" "-fno-builtin" "-fvisibility=hidden" "-ffreestanding" "-mfloat-abi=hard" "-fomit-frame-pointer" "-DVISIBILITY_HIDDEN" "-o" "/home/osboxes/rust/build/x86_64-unknown-linux-gnu/stage2-std/armv7r-none-eabihf/release/build/compiler_builtins-f47ee1d949f1c3ff/out/../../libcompiler_builtins/compiler-rt/lib/builtins/arm/fixdfsivfp.o" "-c" "../../libcompiler_builtins/compiler-rt/lib/builtins/arm/fixdfsivfp.S"
cargo:warning=../../libcompiler_builtins/compiler-rt/lib/builtins/arm/fixdfsivfp.S: Assembler messages:
cargo:warning=../../libcompiler_builtins/compiler-rt/lib/builtins/arm/fixdfsivfp.S:26: Error: selected processor does not support `vmov d7,r0,r1' in ARM mode
cargo:warning=../../libcompiler_builtins/compiler-rt/lib/builtins/arm/fixdfsivfp.S:27: Error: selected processor does not support `vcvt.s32.f64 s15,d7' in ARM mode
cargo:warning=../../libcompiler_builtins/compiler-rt/lib/builtins/arm/fixdfsivfp.S:28: Error: selected processor does not support `vmov r0,s15' in ARM mode
exit code: 1

--- stderr
thread 'main' panicked at '

Internal error occurred: Command "arm-eabi-gcc" "-O2" "-ffunction-sections" "-fdata-sections" "-fPIC" "-ffunction-sections" "-fdata-sections" "-fPIC" "-march=armv7-r" "-fno-builtin" "-fvisibility=hidden" "-ffreestanding" "-mfloat-abi=hard" "-fomit-frame-pointer" "-DVISIBILITY_HIDDEN" "-o" "/home/osboxes/rust/build/x86_64-unknown-linux-gnu/stage2-std/armv7r-none-eabihf/release/build/compiler_builtins-f47ee1d949f1c3ff/out/../../libcompiler_builtins/compiler-rt/lib/builtins/arm/fixdfsivfp.o" "-c" "../../libcompiler_builtins/compiler-rt/lib/builtins/arm/fixdfsivfp.S" with args "arm-eabi-gcc" did not execute successfully (status code exit code: 1).

', /home/osboxes/.cargo/registry/src/github.com-1ecc6299db9ec823/cc-1.0.18/src/lib.rs:2181:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.

warning: build failed, waiting for other jobs to finish...
xerror: build failed
command did not execute successfully: "/home/osboxes/rust/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "armv7r-none-eabihf" "-j" "2" "--release" "--features" "c mem" "-p" "alloc" "-p" "compiler_builtins" "--manifest-path" "/home/osboxes/rust/src/rustc/compiler_builtins_shim/Cargo.toml" "--message-format" "json"
expected success, got: exit code: 101
thread 'main' panicked at 'cargo must succeed', bootstrap/compile.rs:1119:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.
failed to run: /home/osboxes/rust/build/bootstrap/debug/bootstrap dist --target armv7r-none-eabihf
Build completed unsuccessfully in 0:50:21

chat_transcript.log

Alright – random question for someone that knows Rust's build setup better than I do: I'm working to add (little-endian) a new target for Cortex R5F MCUs using the suitable Linaro toolchain, similar to the approach taken here https://github.com/rust-lang/rust/pull/50813
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13:49 kenkeiter
I *think* I'm running into a weird issue with Rust's fork of compiler-rt. It appears that a patch has been added upstream to deal with specifics of -mfloat-abi=hard (see https://github.com/llvm-mirror/compiler-rt/blob/master/lib/builtins/arm/fixdfsivfp.S#L22-L25) that aren't in Rust's fork of compiler-rt (https://github.com/rust-lang/compiler-rt/blob/master/lib/arm/fixdfsivfp.S).
kenkeiter
When I build, I'm getting a few errors that correspond to these (https://github.com/rust-lang/compiler-rt/blob/master/lib/arm/fixdfsivfp.S#L22-L24) instructions, prefixed with "Error: selected processor does not support <...> in ARM mode"
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japaric
kenkeiter: rust-lang/rust is not using the master branch of rust-lang/compiler-rt
japaric
the version it's using does include the patch you mention. This is it https://github.com/rust-lang/compiler-rt/blob/8964c7a0c4d1dc8c45b5adee6fe5ae3db057ab98/lib/builtins/arm/fixdfsivfp.S
13:54 kenkeiter
Hmm, then I'm guessing that somehow COMPILER_RT_ARMHF_TARGET is not defined.
japaric
kenkeiter: what's the full error message? I'd like to see what instruction the compiler is rejecting
kenkeiter
Sure; I'll paste a couple things into a gist for you. Give me two seconds...
japaric
also I find odd that the other ARM targets are not running into this
japaric
kenkeiter: what's the name of the new target?
kenkeiter
Me too, but I was able to build https://github.com/paoloteti/ti-hercules-bsp successfully.
japaric
the build script in compiler-rt using the target triple to decide which .c / .s files to builds
japaric
to build**
kenkeiter
Right; and it should be able to build this one. The new target is called "armv7r-none-eabihf"
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japaric
kenkeiter: it could also be that the 'cc' crate needs to learn about the new target
japaric
the cc crate chooses which C flags to use based on the target name
japaric
kenkeiter: (also, if are working with Cortex-R devices you may want to say hello in this thread https://github.com/rust-embedded/wg/issues/183)
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kenkeiter
Ahhh interesting. One sec. Almost done with that gist.
kenkeiter
@japaric https://gist.github.com/kenkeiter/c2add8253ba10791566a2d13c42e6442
kenkeiter
(yes, the LLVM features are a little verbose/redundant at the moment – I was running into issues earlier so I brought them in from the LLVM td)
kenkeiter
(just added the Dockerfile, as well)
japaric
kenkeiter: thanks, looking
kenkeiter
@japaric Thank you :)
kenkeiter
First attempt at digging into this layer of the Rust – so I apologize if something obvious is wrong.
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japaric
kenkeiter: hmm, weird. The armebv7r target which has been already commited doesn't work for me. The build also fails while compiling compiler-rt and with a similar error message
kenkeiter
I'm guessing you're using the Linaro toolchain?
japaric
kenkeiter: the one in the dockerfile
kenkeiter
Yeah, that's the right one...
japaric
the armeb-eabi linaro one
kenkeiter
Ah, you're trying to build the eb target?
kenkeiter
Sorry, I had misread.
japaric
yes, the eb one but it also fails
kenkeiter
That's strange – that one builds properly for me.
japaric
what I don't understand is how the ti-hercules-bsp does compile correctly
japaric
since I don't have the armeb toolchain in my PATH
kenkeiter
I added it to my PATH...
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japaric
kenkeiter: interesting when you compile the ti-hercules-bsp repo you compile the compiler-builtins crate but the rlib doesn't contain the fixdfsivfp symbol which causes problem in the rust build system
kenkeiter
That is interesting... I'm not sure what a fix looks like for that, since I don't have enough familiarity there :-/ Happy to rubber-duck though...
japaric
kenkeiter: ah ok I see the difference. when using cargo-xbuild the compiler-builtins crate is compiled without the "c" Cargo feature so the .c / .s files never get compiled
japaric
otoh when using the rust build system that crate is compiled with the "c" feature enabled
japaric
so there are few things to fix here
japaric
first the cc crate needs to gain support for the armebv7r target and for your new target
japaric
then we'll probably need to tweak the compiler-builtins crate so that it build with the "c" feature enabled for both targets
japaric
I'm not familar with using gcc to compiler code for the cortex-r architecture though. What are some common flags one use in that case? other than -march=armv7-r
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kenkeiter
japaric: I'm happy to try to dig into that, if you wish, with the caveat that I have almost no idea what I'm doing (:
kenkeiter
japaric: Probably specification of the float ABI that's in use (i.e. `-mfloat-abi=hard`)
kenkeiter
fpu specification, as well (i.e. `-mfpu=vfpv3-d16`)
japaric
kenkeiter: compare https://gist.github.com/japaric/3ef9723ef60c6f91115047e3770fadcd#file-armebv7r-none-eabihf-out-L25 and https://gist.github.com/japaric/3ef9723ef60c6f91115047e3770fadcd#file-thumbv7m-none-eabi-out-L27
japaric
the armeb target is wrong; it's using cc when it should use an arm compiler
kenkeiter
So, for the eb target (at least, via its Dockerfile), there's an env var being set that points to the cc provided in the Linaro toolchain
kenkeiter
https://github.com/paoloteti/rust/blob/4897093cfd858fb10ce538e86f7b549cb199db13/src/ci/docker/disabled/dist-armebv7r-none-eabihf/Dockerfile
japaric
kenkeiter: the -march needs to be fixed around here https://github.com/alexcrichton/cc-rs/blob/master/src/lib.rs#L1245
japaric
based on the target name
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kenkeiter
AH, yes, that would be a problem...
japaric
kenkeiter: the gist contains parts of a Cargo project. You can use it test a local checkout of the cc crate. See https://gist.github.com/japaric/3ef9723ef60c6f91115047e3770fadcd#file-cargo-toml-L12
japaric
kenkeiter: the default compiler is set around here https://github.com/alexcrichton/cc-rs/blob/master/src/lib.rs#L1675-L1678 I think arm-none-eabi would be a good default since it's what most Linux distros provide and it can always be overridden
14:52 kenkeiter
Good hint! Okay. So I'm guessing the best approach here would be to modify cc-rs to include some new target matching for ARM (specifically, something that detects the "eabihf" suffix and adds the appropriate flag), and then attempt to build Rust using the modified cc crate.
kenkeiter
Right, makes sense.
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kenkeiter
Alright; I'll give that a shot! Thanks for your help. Generally haven't needed to dig this deep in the past, so the guidance is definitely appreciated.
kenkeiter
japaric: ^
15:00 japaric
kenkeiter: yw. I don't know of a way to make the rust build system use a local checkout of a crate like cc so it may be better to test that the compiler-builtins crate builds by calling `cargo build` from its directory -- previous addition of [replace] to its Cargo.toml
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kenkeiter
Well, I probably could get it to work with a local crate, but I'm guessing it'd be a pretty violent and disturbing process.

Dockerfile

FROM ubuntu:16.04

RUN apt-get update && apt-get install -y --no-install-recommends \
  g++ \
  make \
  file \
  curl \
  ca-certificates \
  python2.7 \
  git \
  cmake \
  sudo \
  xz-utils \
  bzip2 \
  libssl-dev \
  pkg-config


COPY scripts/sccache.sh /scripts/
RUN sh /scripts/sccache.sh

ENV BASE_URL=https://releases.linaro.org/components/toolchain/binaries/latest/arm-eabi/
ENV GCC_LINARO=gcc-linaro-7.3.1-2018.05-x86_64_arm-eabi

RUN curl -sL $BASE_URL/$GCC_LINARO.tar.xz | tar -xJ

ENV PATH=$PATH:/$GCC_LINARO/bin

ENV TARGET=armv7r-none-eabihf

ENV CC_armv7r_none_eabihf=arm-eabi-gcc \
    CFLAGS_armv7r_none_eabihf="-march=armv7-r"

ENV RUST_CONFIGURE_ARGS --disable-docs

ENV SCRIPT python2.7 ../x.py dist --target $TARGET

features: "+v7,+armv7-r,+db,+dsp,+dsp,+hwdiv,+rclass,+r5,+ras,+vfp3,+d16,+slow-fp-brcc,+hwdiv-arm,+slowfpvmlx,+thumb2

There are redundant features here: for example v7 is superfluous because part of llvm_target (the v7 in the triple name), the same for v7r, also thumb2 is already part of +v7. +dsp and +hwdiv are superfluous too.

BTW the idea is to provide only a set of minimal features for a give target and to override/extend features at command line.