Fix `rustc` >= nightly-2021-03-05 builds (i.e. LLVM 12)

[ojeda]

https://github.com/Rust-for-Linux/linux/pull/134/checks?check_run_id=2161428668

[    0.270313] module rust_example_3: unsupported RELA relocation: 311

[ojeda]

See also
https://lore.kernel.org/rust-for-linux/CAMmOe3SaBn9+XzjhZC8QxmZnHQkvB0R=nV4NaRRyMRF6EfcvvA@mail.gmail.com/

[jabedude]

Relevant relocation from elf.h:

#define R_AARCH64_ADR_GOT_PAGE  311     /* P-page-rel. GOT off. ADRP 32:12.  */

I took a look at the logs for the CI failure and was wondering if there's a way to grab artifacts from the build run. I couldn't find a way

[ojeda]

I took a look at the logs for the CI failure and was wondering if there's a way to grab artifacts from the build run.

There is currently no way that I am aware of, because we do not upload them (the reason is that, when I tried a couple months ago, it turned out it failed from time to time, it was not reliable).

[ojeda]

This was due to rustc's upgrade to LLVM 12 (rust-lang/rust#81451) starting in nightly 2021-03-05.

Possibly also related to rust-lang/rust#83335.

[alex]

Definitely looks related, we set relocation-model: static in our targets, so if that's not being respected with LLVM 12, that'd definitely do it.

…

On Mon, Mar 22, 2021 at 8:38 PM Miguel Ojeda ***@***.***> wrote: This was due to rustc's upgrade to LLVM 12 (rust-lang/rust#81451 <rust-lang/rust#81451>) starting in nightly 2021-03-05. Possibly also related to rust-lang/rust#83335 <rust-lang/rust#83335>. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#135 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAAGBD653K74AIZPITJJTLTE7PGTANCNFSM4ZR65VKA> .

-- All that is necessary for evil to succeed is for good people to do nothing.

[ojeda]

Yeah, I tried setting "position-independent-executable": false in case relocation-model was somehow being overridden now by the former, but it didn't help. Not sure how they interact in any case.

[ojeda]

LLVM issue: https://bugs.llvm.org/show_bug.cgi?id=49693

[alex]

PR on the Rust side: rust-lang/rust#83592