riscv rt linker issue with cargo build

[yashwanthsinghm]

We have used riscv_rt in our current projects and encountered a couple of issues:

Cargo release builds are happening but when we compile for debug its giving following error.

• Linker Issue:  ``` rust-lld: error: <internal»:(.eh_frame+0x40): relocation R_RISCV_32_PCREL out of range: 2147486966 is not in I-2147483648, 2147483 6471; references ```
  

github : Strange21/RISCV: software for RISCV

In-order to reproduce the error

1. cd riscv-hal
2. cargo build --example gptimer

Issue

error: linking with 'rust-lld' failed: exit status: 1
= note: "rust-lld" "-flavor" "gnu" "/var/folders/bn/73c2thl17734d902lypvxbpc0000gn/T/rustcf4Z0vW/symbols.0" "<2 object files omitted»" "-
-as-needed" "-Bstatic" "/Users/IKL2KOR/Desktop/shakti_riscv_hal/examples/gpio_applns/target/riscv64imac-unknown-none-elf/debug/deps/{libshak ti_riscy_hal-e9fb2d117581f3a1. rlib, libtock_registers-dd0b6693e8c40f2b.rlib, libriscv_rt-a141fe7383d82ded. rib, libriscv-bc6c60484b95b10b.rlib,
libcritical_section-e493a1cc7896740d. rlib, libriscv_pac-a4f795429843822a. rlib, libembedded_hal-ab4e22761e14a865.rlib}.rlib" "<sysroot>/lib/rus
tlib/riscv64imac-unknown-none-elf/lib/{librustc_std_workspace_core-*,libcore-*,libcompiler_builtins-*}.rlib" "-Bdynamic" "-z".
"noexecstack"
"-L" "/Users/IKL2KOR/Desktop/shakti_riscv_hal/examples/gpio_applns/target/riscv64imac-unknown-none-elf/debug/build/riscv-rt-5a95d4c5a1c18589 /out" "-L" "/Users/IKL2KOR/Desktop/shakti_riscv_hal/examples/gpio_applns/target/riscv64imac-unknown-none-elf/debug/build/shakti_riscv_hal-8e
= note: rust-lld: error: «internal»: (-eh_frame+0x1c): relocation R_RISCV_32_PCREL out of range: 2147486584 is not in I-2147483648, 2147483
6471; references '.LO '
»> defined in /Users/IKL2KOR/. rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/riscv64imac-unknown-none-elf/lib/libcore
-9699b3174c9bc206. rlib(core-9699b3174c9bc206, core. c4f5009eca0c9ae-cgu.0.rcgu.o)
rust-lld: error: <internal»:(.eh_frame+0x40): relocation R_RISCV_32_PCREL out of range: 2147486966 is not in I-2147483648, 2147483
6471; references
»> defined in /Users/IKL2KOR/. rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/riscv64imac-unknown-none-elf/lib/libcore
-9699b3174c9bc206. rlib(core-9699b3174c9bc206. core. c4f5009eca@c9ae-cgu.0.rcgu.o)
rust-lld: error: <internal>: (.eh_frame+0x64): relocation R_RISCV_32_PCREL out of range: 2147487738 is not in I-2147483648, 2147483
647]; references 'LO '
»> defined in /Users/IKL2KOR/. rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/riscv64imac-unknown-none-elf/lib/libcore
-9699b3174c9bc206. rlib(core-9699b3174c9bc206.core.c4f5009ecac9ae-cgu.0.rcgu.o)
rust-lld: error: «internal>: (.eh_frame+0x84): relocation R_RISCV_32_PCREL out of range: 2147487736 is not in I-2147483648, 2147483
6471; references
'.LO'
»> defined in /Users/IKLKOR/. rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/riscv64imac-unknown-none-elf/lib/libcore
-9699b3174c9bc206. rlib(core-9699b3174c9bc206. core. c4f5009eca@c9ae-cgu.0.rcgu.o)
rust-lld: error: ‹internal>: (.eh_frame+0xa4): relocation R_RISCV_32_PCREL out of range: 2147487738 is not in I-2147483648, 2147483
6471; references
'LO'
›>› defined in /Users/IKL2KOR/. rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/riscv64imac-unknown-none-elf/lib/libcore
-9699b3174c9bc206. rlib(core-9699b3174c9bc206. core. c4f5009eca0c9aбe-cgu.0.rcgu.o)
rust-lld: error: «internal»:(.eh_frame+0xc4): relocation R_RISCV_32_PCREL out of range: 2147487782 is not in I-2147483648, 2147483
647]; references '.LO '
»› defined in /Users/IKLKOR/. rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/riscv64imac-unknown-none-elf/lib/libcore
-9699b3174c9bc206. rlib(core-9699b3174c9bc206. core. c4f5009eca@c9a6e-cgu.0.rcgu.o)
rust-lld: error: internal»: (.eh_frame+0xe4): relocation R_RISCV_32_PCREL out of range: 2147487808 is not in I-2147483648, 2147483
647]; references 'LO '
›>› defined in /Users/IKL2KOR/. rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/riscv64imac-unknown-none-elf/lib/libcore
-9699b3174c9bc206. rlib(core-9699b3174c9bc206. core. c4f5009eca0c9a6e-cgu.0.rcgu.o)

[romancardenas]

Related: #153

[romancardenas]

I was able to reproduce your issue on my machine. I then changed riscv-rt 13.0 to the current version in GitHub and it compiled without issues. Not sure what the problem is, we need to study it more deeply.

[romancardenas]

we removed references to eh_frame in master: 2ce267a

This may be the reason why it now works. We should release a new version of riscv-rt ASAP with this change.

[yashwanthsinghm]

Hi @romancardenas

If you look into cargo.toml we have already updated riscv_rt to 13.0, cargo build -r --example gptimer works for us which is a release build. But cargo build --example gptimer is giving above linker issue.

It is not just in this project but this is reflected in other projects as well, for example you can check out this as well.

• GitHub clone : https://github.com/yashwanthsinghm/shakti_riscv_hal

• cd examples

• cd gpio_applns

• cargo build

[romancardenas]

Try pointing to GitHub's master branch instead of crates.io's version. It should work.

I'll publish a 0.13.1 if it does.

[yashwanthsinghm]

Thank you @romancardenas It works. We have tested it with two different projects using the GitHub master branch. You can proceed to publish it

[yashwanthsinghm]

Hi @romancardenas ,

new issue encountered when i try to use semihosting with riscv_rt, please check out this.

git : https://github.com/imrank03/riscv_semi.git

its just a basic hprintln!, giving a linker issue is it something to do with riscvrt?

error: linking with `rust-lld` failed: exit status: 1
  |
  = note: LC_ALL="C" PATH="/home/yash/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/bin:/home/yash/.cargo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin" VSLANG="1033" "rust-lld" "-flavor" "gnu" "/tmp/rustcrqWxx0/symbols.o" "<1 object files omitted>" "--as-needed" "-Bstatic" "/home/yash/Desktop/riscv_semi/target/riscv64imac-unknown-none-elf/release/deps/{libriscv_semihosting-9885f64fe96df006.rlib,libriscv_rt-51d68b33f01ce5fb.rlib,libriscv-59dab6363963a7ed.rlib,libcritical_section-e9f5889c719a3841.rlib,libriscv_pac-f89df8fa6230efac.rlib,libembedded_hal-5d1dcc1d7cb422dd.rlib,libpanic_halt-1ef63fdfdece3a56.rlib}" "/home/yash/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/riscv64imac-unknown-none-elf/lib/{librustc_std_workspace_core-7f86cd12f52bcad5.rlib,libcore-30a786714711bc78.rlib,libcompiler_builtins-40c1ef24ccedc865.rlib}" "-Bdynamic" "-z" "noexecstack" "-L" "/home/yash/Desktop/riscv_semi/target/riscv64imac-unknown-none-elf/release/build/riscv-rt-6ad9b6d4d4ba936a/out" "-o" "/home/yash/Desktop/riscv_semi/target/riscv64imac-unknown-none-elf/release/deps/riscv_semi-87ccd1d41771d2dd" "--gc-sections" "-O1" "--strip-debug" "-Tmemory.x" "-Tlink.x"
  = note: some arguments are omitted. use `--verbose` to show all linker arguments
  = note: rust-lld: error: undefined symbol: _critical_section_1_0_acquire
          >>> referenced by riscv_semihosting.8936a401a212ccd8-cgu.0
          >>>               riscv_semihosting-9885f64fe96df006.riscv_semihosting.8936a401a212ccd8-cgu.0.rcgu.o:(riscv_semihosting::export::machine::hstdout_str::hfc1c719f4714c606) in archive /home/yash/Desktop/riscv_semi/target/riscv64imac-unknown-none-elf/release/deps/libriscv_semihosting-9885f64fe96df006.rlib
          
          rust-lld: error: undefined symbol: _critical_section_1_0_release
          >>> referenced by riscv_semihosting.8936a401a212ccd8-cgu.0
          >>>               riscv_semihosting-9885f64fe96df006.riscv_semihosting.8936a401a212ccd8-cgu.0.rcgu.o:(riscv_semihosting::export::machine::hstdout_str::hfc1c719f4714c606) in archive /home/yash/Desktop/riscv_semi/target/riscv64imac-unknown-none-elf/release/deps/libriscv_semihosting-9885f64fe96df006.rlib
          

error: could not compile `riscv_semi` (bin "riscv_semi") due to 1 previous error
yash@yash-VirtualBox:~/Desktop/riscv_semi$  ```

[romancardenas]

That sounds more like you have not activated any feature flag to enable a valid implementation of critical_section. If your target is single HART, try enabling the riscv's critical-section-single-hart feature.

[romancardenas]

The patch is here: https://github.com/rust-embedded/riscv/tree/rvrt-patch

@yashwanthsinghm can you please run your apps using this branch and confirm it works?

[imrank03]

riscv's critical-section-single-hart feature

Hi @romancardenas,

I made changes and enabled the riscv's critical-section-single-hart feature. However, I was still encountering an error. After applying your patch to update the dependencies, the code compiled without any errors. It seems there might be an issue with riscv, but I could be wrong.

Could you please check with riscv version 0.12.1? Below is the relevant Cargo.toml configuration:

[dependencies]
riscv = { git = "https://github.com/rust-embedded/riscv", branch = "rvrt-patch", features = ["critical-section-single-hart"] }
riscv-rt = { git = "https://github.com/rust-embedded/riscv", branch = "rvrt-patch" }
riscv-semihosting = { version = "0.1.2" }
panic-halt = "1.0.0"

Here is the working Git repository: (https://github.com/imrank03/riscv_semi).

Note: Tested on board, and it is working with these changes.

Let me know your thoughts.

[romancardenas]

You are experiencing an interesting issue regarding how Cargo deals with dependencies. Let's leave your riscv dependency pointing to crates.io.

The riscv-rt crate depends on riscv. However, when you use the GitHub version of riscv-rt, then riscv-rt depends on the GitHub version of riscv, not the one published in crates.io.

In your dependencies, you are mixing the crates.io version of riscv and the GitHub version of riscv-rt. As the GitHub version of riscv-rt depends on the GitHub version of riscv, you can see in the compilation traces that you are building two different versions of riscv:

    ...
   Compiling riscv v0.12.0 (https://github.com/rust-embedded/riscv?branch=rvrt-patch#f16c833d)
   Compiling riscv v0.12.1
   ...

Then, in your example, you don't use riscv at all. You only use riscv-rt, riscv-semihosting, and panic-halt. Thus, Cago just ignores your riscv dependency, which is not added. However, your riscv dependency is the one enabling the critical section feature!

Modify your example. You can add something like use riscv as _; (this is exactly the same trick used with panic-halt). Now, Cargo will notice that you want to use the riscv dependency in your Cargo.toml file and use it. I tested it in my machine and works.

Working examples:

#![no_std]
#![no_main]

use panic_halt as _;
use riscv as _; // We tell Cargo that we want to use our riscv dependency
use riscv_rt::entry;
use riscv_semihosting::{debug, hprintln};
// use semihosting::println;

#[entry]
fn main() -> ! {
    hprintln!("Hello, world!");
    debug::exit(debug::EXIT_FAILURE);
    loop {}
}

I prefer this other, though:

#![no_std]
#![no_main]

use panic_halt as _;
use riscv_rt::entry;
use riscv_semihosting::{debug, hprintln};
// use semihosting::println;

#[entry]
fn main() -> ! {
    hprintln!("Hello, world!");
    debug::exit(debug::EXIT_FAILURE);
    loop {
        riscv::asm::wfi(); // explicitly use riscv, so Cargo does not drop it
    }
}

Once the patch is on crates.io, you will not face this issue, as all your dependencies point to crates.io and there will not be multiple riscv versions

[imrank03]

Thank you for the detailed explanation! I truly appreciate your insights and guidance. I'll make the changes as you suggested.

Thanks again for your help! 😊

[yashwanthsinghm]

Thank you @romancardenas for clearing out confusion, the patch branch works. I hope it reflects on crates.io in latest release.