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Add arm64 cross-build images targeting Ubuntu 16.04#754

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mthalman merged 5 commits intodotnet:mainfrom
sbomer:glibcFix
Jan 17, 2023
Merged

Add arm64 cross-build images targeting Ubuntu 16.04#754
mthalman merged 5 commits intodotnet:mainfrom
sbomer:glibcFix

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@sbomer sbomer commented Jan 4, 2023

@janvorli @MichaelSimons PTAL. I can't seem to add reviewers directly.

This is adding an Ubuntu 20.04 image with an arm64 Ubuntu 16.04 rootfs that we can use to build against a lower glibc version than we currently support. The plan is to use this image at least for the .NET 7 part of dotnet/runtime#69361.

Locally, I've used these steps to build a container that can build coreclr with the --pgoinstrument argument. Without the profile library build, the build fails with

ld.lld: error: cannot open /rootfs/usr/lib/llvm-9/lib/clang/9.0.1/lib/linux/libclang_rt.profile-aarch64.a: No such file or directory

Building this library and copying it into the rootfs fixes this.

@janvorli I would appreciate if you could also review the logs here to make sure everything looks ok: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/137325/logs/467. I started with instructions at https://llvm.org/docs/HowToCrossCompileLLVM.html and https://llvm.org/docs/HowToCrossCompileBuiltinsOnArm.html, then had to play around with the arguments and use a mix of CMAKE variables and flags like --sysroot (-DCMAKE_SYSROOT was not working as I expected). The logs show that /usr/lib/llvm-9/lib/clang/9.0.1/include is still being used as an include path - I am not sure if this is a problem, so I'd appreciate your eyes on this.

@ghost ghost added the area-dockerfiles label Jan 4, 2023
@sbomer sbomer changed the title Target Ubuntu 16.04 in arm64 cross-build images Add arm64 cross-build images targeting Ubuntu 16.04 Jan 13, 2023
@sbomer sbomer marked this pull request as ready for review January 14, 2023 00:56
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The logs show that /usr/lib/llvm-9/lib/clang/9.0.1/include is still being used as an include path

The same happens for .NET crossbuild, so it is ok. It seems like these are compiler internal headers for intrinsics and few other things.


In certain cases, it is necessary to run custom logic before and after the Dockerfiles are built. For example, to build the Dockerfiles that are used for cross-gen builds, the rootfs that gets copied into the Docker image needs to be built on the host OS. To support these scenarios a `pre-build` or `post-build` bash or PowerShell script can be placed in a `hooks` folder next to the Dockerfile. The scripts will get invoked by the build process.

Note that multi-stage docker builds can be used to accomplish the same without build hooks, and are easier to iterate on locally because this takes advantage of docker image caching to avoid re-running steps when nothing has changed (whereas pre-build hooks run every time the dockerfile is built).
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I like this. Hadn't looked closely at the original implementation to see that this could be improved. It was implemented before multi-stage Dockerfiles were even supported.

- Remove redundant toolchain option
- Rename to BUILD_CXX_FLAGS
- Indent cmake arguments
@sbomer sbomer requested a review from janvorli January 17, 2023 18:21
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sbomer commented Jan 17, 2023

@mthalman @MichaelSimons would you mind merging this? I don't have permission. Thanks!

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3 participants