error: unable to get target for 'riscv32imac-unknown-none-elf'

[japaric]

STR

$ cat src/lib.rs

#![no_std]

#[no_mangle]
pub fn foo(x: u32, y: u32) -> u32 {
    x + y
}

$ cargo build --target riscv32imac-unknown-none-elf --release
$ cargo objdump --target riscv32imac-unknown-none-elf -v -- -d target/riscv32imac-unknown-none-elf/release/libfoo.rlib
"/home/japaric/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/bin/llvm-objdump" "-triple" "riscv32imac-unknown-none-elf" "-d" "target/riscv32imac-unknown-none-elf/release/libfoo.rlib"

target/riscv32imac-unknown-none-elf/release/libfoo.rlib(foo-5f01dd28752961b9.foo0-d59093d565f158ef2f92ae2d0a10a47.rs.rcgu.o):     file format ELF32-riscv

/home/japaric/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/bin/llvm-objdump: 'foo-5f01dd28752961b9.foo0-d59093d565f158ef2f92ae2d0a10a47.rs.rcgu.o': can't find target: : error: unable to get target for 'riscv32imac-unknown-none-elf', see --version and --triple.
.

The problem is that the triple passed to llvm-objdump is not a valid LLVM triple; riscv32imac is not a valid LLVM architecture name.

A solution to this problem would be to use pass -arch-name, instead of -triple, to llvm-objdump. The argument to pass would then have to be a valid LLVM architecture (see cargo objdump -- -version) so we would need to map the Rust architecture (see rustc --target $T --print cfg) into a LLVM architecture. We have to be careful with the thumbv* targets which have target_arch: "arm" but actually map to "thumb" LLVM architecture.

[japaric]

cc @rust-embedded/riscv

[danc86]

Makes me wish we had kept the rust arch name as "riscv" instead of "riscv32" ... but there is no nice solution here, the GNU toolchain insists it is "riscv32" or "riscv64" not "riscv". :-(

[japaric]

Also working on this while I work on #15

[dvc94ch]

I noticed readelf is missing, how come?

…

On Sat, Aug 25, 2018, 20:38 Jorge Aparicio ***@***.***> wrote: Also working on this while I work on #15 <#15> — You are receiving this because you are on a team that was mentioned. Reply to this email directly, view it on GitHub <#17 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAtRr7UveBkJ0_D_DZeHeriOF0nbagThks5uUZmegaJpZM4VzRk_> .

[japaric]

@dvc94ch probably because no one asked for it. You can send a PR to add it. You can use rust-lang/rust#51962 as a reference.

[dvc94ch]

Good to know. Put it on my Todo list, thanks.

…

On Sun, Aug 26, 2018, 11:25 Jorge Aparicio ***@***.***> wrote: @dvc94ch <https://github.com/dvc94ch> probably because no one asked for it. You can send a PR to add it. You can use rust-lang/rust#51962 <rust-lang/rust#51962> as a reference. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#17 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAtRr3OWQC-Jd9H51jgA-2yRfp3RBouLks5uUmmJgaJpZM4VzRk_> .

[japaric]

PR #19 fixes this