Investigate possibility of requesting IBM runner access for {ppc64le, s390x}

[jieyouxu]

Relevant context

• Expanding Open Source Access: Hosted GitHub Actions Runners Now Available for IBM Z, IBM LinuxONE, and IBM Power.
• IBM/actionspz on-boarding guide
• https://github.com/IBM/actionspz

Discussions

• #t-infra > IBM runners for GitHub Actions

Steps

• Periodically check if any of current proposals are accepted.
  • 2025-06-28: LLVM's proposal seems to be okay, though it does require installing a Github App to the account.
• Determine which rust-lang/* repos would like to request access to {ppc64le, s390x} runners
• Draft proposals for each repo that would like to request access (or combined?)

[tgross35]

For possible repos:

• stdarch: https://github.com/rust-lang/stdarch/blob/1b4d15df12079504942d0a3f1030b2039b8a776c/.github/workflows/main.yml#L65-L82
• compiler-builtins: https://github.com/rust-lang/compiler-builtins/blob/add44a716f996401dac618417519ac31185b80c8/.github/workflows/main.yaml#L67-L72,
• libc: https://github.com/rust-lang/libc/blob/aa5bbcc79d66504d8044e1c9a6a78aafe35b3535/.github/workflows/ci.yaml#L185-L188