[apple-mobile][infra] Internal CI is failing with Bad CPU type in executable

[matouskozak]

Internal apple-mobile physical device CI is failing with Bad CPU type in executable error message.

• Build: https://dev.azure.com/dnceng/internal/_build/results?buildId=2679981 (failing on previous builds as well)
• Affected CI: ios_arm64_release_allsubsets_mono, tvos_arm64_release_allsubsets_mono, ios_arm64_release_allsubsets_nativeaot, tvos_arm64_release_allsubsets_nativeaot

Crash log:

<PATH>/p/build/apple/AppleBuild.targets(253,5): error : Precompiling failed for <PATH>/<SUB_PATH_2>/publish/System.Collections.dll: An error occurred trying to start process '<PATH>/p/build/cross/mono-aot-cross' with working directory '<PATH>/<SUB_PATH_2>publish'. Bad CPU type in executable [/private<PATH>/<SUB_PATH_2>/publish/ProxyProjectForAOTOnHelix.proj]

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[steveisok]

This is actually expected. The architectures that you build and run the aot compiler on have to match. The internal build hosted pool is arm64, but the tests build on x64. On PR's, the build and test architecture is x64.

To get it to work we would have to cross compile the aot compiler for x64. Not sure it's worth the effort.

[matouskozak]

This is actually expected. The architectures that you build and run the aot compiler on have to match. The internal build hosted pool is arm64, but the tests build on x64. On PR's, the build and test architecture is x64.

To get it to work we would have to cross compile the aot compiler for x64. Not sure it's worth the effort.

Indeed, another option would be not to build the tests on Helix (set /p:BuildTestsOnHelix=false) and instead build it on the azdo build VMs which are arm64.

Not sure if we have internal x64 macOS pool we could switch the apple mobile jobs so that it matches the public config?

[am11]

Not sure it's worth the effort.

I believe it's worth switching to arm64 for Apple platforms primarily, since the last x64 Mac Apple released was in 2023 and they don't have plans to revive this discontinued product: #108570.

[steveisok]

I believe it's worth switching to arm64 for Apple platforms primarily, since the last x64 Mac Apple released was in 2023 and they don't have plans to revive this discontinued product: #108570.

I agree, but one of the things holding us back is the public hosted pool where x64 is the only option.