build: use aarch64 Clang if cross-compiling for darwin on aarch64 #22436

1. 
   fanquake commented at 12:39 pm on July 13, 2021: member

   If we’re cross-compiling for darwin on aarch64 hardware, we need to use a Clang that will run on that hardware.

   Only tested in a Linux Docker container (aarch64-unknown-linux-gnu), running on an Apple M1 mac-mini (aarch64-apple-darwin20.5.0).

2. build: use aarch64 Clang if cross-compiling for darwin on aarch64

   If we're cross-compiling for darwin on aarch64 hardware, we need need to
   use a Clang that will run on that hardware.
   
   Only tested in a Linux Docker container (aarch64-unknown-linux-gnu),
   running on an Apple M1 mac-mini (aarch64-apple-darwin20.5.0).

   54c7754f31
3. fanquake added the label Build system on Jul 13, 2021
4. 
   hebasto commented at 12:55 pm on July 13, 2021: member

   If we’re cross-compiling for darwin on aarch64 hardware, we need to use a Clang that will run on that hardware.

   To be precise, you mean “run natively”, as x86 code could be run on aarch64 hardware via Rosetta layer, right?

5. 
   fanquake commented at 1:01 pm on July 13, 2021: member

   To be precise, you mean “run natively”, as x86 code could be run on aarch64 hardware via Rosetta layer, right?

   I’m talking about cross-compiling for Darwin, using Linux, on aarch64 hardware. I’m not sure what Rosetta is going to help with in that case.

6. 
   hebasto commented at 1:37 pm on July 13, 2021: member

   Concept ACK. Cannot test on aarch64 hardware w/o virtualization.
7. 
   laanwj commented at 1:43 pm on July 13, 2021: member

   Concept ACK
8. 
   sipa commented at 6:33 pm on July 13, 2021: member

   I’ll run a guix build on aarch64 hardware (Odroid N2+).
9. 
   DrahtBot commented at 7:12 pm on July 13, 2021: member

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Conflicts

   Reviewers, this pull request conflicts with the following ones:

   • #21778 by fanquake

   If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

10. 
    sipa commented at 7:16 pm on July 13, 2021: member

    What guix HOSTS= do I use?
11. 
    fanquake commented at 1:12 am on July 14, 2021: member

    What guix HOSTS= do I use?

    HOSTS="x86_64-apple-darwin18"

12. 
    hebasto commented at 5:05 pm on July 17, 2021: member

    Tested 54c7754f3118bcb6ea598246c9c0458043de4af9 for x86_64-apple-darwin18 host in hirsute Docker container on macOS M1, and faced a bug which is fixed in #22448.

    ~Maybe rebase this PR on top of the #22448?~

13. 
    hebasto commented at 5:42 pm on July 17, 2021: member

    ACK 54c7754f3118bcb6ea598246c9c0458043de4af9, I agree it can be merged (fix in #22448 is orthogonal to this one).
14. fanquake requested review from dongcarl on Jul 18, 2021
15. fanquake merged this on Jul 20, 2021
16. fanquake closed this on Jul 20, 2021

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17. fanquake deleted the branch on Jul 20, 2021
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Contributors
fanquake hebasto laanwj sipa DrahtBot

Review Requested
dongcarl

Labels
Build system