Cross compilation on Ubuntu 22.04 to ARM from AMD

[saariniemi]

In dotnet9 is cross compilation still supported on Ubuntu? What is required?

Steps to reproduce

1. I have installed dotnet9
2. I have run script from documentation:
   https://learn.microsoft.com/en-us/dotnet/core/deploying/native-aot/cross-compile#linux
3. Created new webapiaot
   dotnet new webapiaot
4. Run publish
   dotnet publish -f net9.0 -r linux-arm64 -c Release

Exception:
error : The PrivateSdkAssemblies ItemGroup is required for _ComputeAssembliesToCompileToNative

Real scenario

In our production we have used a docker container for cross compiling.

Following script is incompatible with latest docker images (9.0-noble) and there is no documentation provided how to enable cross compilation on that image.

I have also tried directly to use the 9.0-noble-arm container ... but I get an exception wheb executing dotnet publish.

sudo dpkg --add-architecture arm64 sudo bash -c 'cat > /etc/apt/sources.list.d/arm64.list <<EOF deb [arch=arm64] http://ports.ubuntu.com/ubuntu-ports/ jammy main restricted deb [arch=arm64] http://ports.ubuntu.com/ubuntu-ports/ jammy-updates main restricted deb [arch=arm64] http://ports.ubuntu.com/ubuntu-ports/ jammy-backports main restricted universe multiverse EOF' sudo sed -i -e 's/deb http/deb [arch=amd64] http/g' /etc/apt/sources.list sudo sed -i -e 's/deb mirror/deb [arch=amd64] mirror/g' /etc/apt/sources.list sudo apt update sudo apt install -y clang llvm binutils-aarch64-linux-gnu gcc-aarch64-linux-gnu zlib1g-dev:arm64

Environment

.NET SDK:
Version: 9.0.100
Commit: a2bc464e40
Workload version: 9.0.100-manifests.6bf02610
MSBuild version: 17.12.7+a2bc464e4

Runtime Environment:
OS Name: ubuntu
OS Version: 22.04
OS Platform: Linux
RID: ubuntu.22.04-x64

[marcpopMSFT]

@richlander I think you're the expert here for container compilation. Any ideas?

[richlander]

Try this page: https://github.com/dotnet/runtime/blob/main/src/coreclr/nativeaot/docs/README.md

[ladeak]

I have the same issue on WSL (Ubuntu 24.04.1 LTS). It works fine to compile linux-x64, but linux-arm64 build fails with:

> dotnet publish -c Release -r linux-x64 --self-contained
Restore complete (1.2s)
  WebApplication6 succeeded (32.0s) → bin/Release/net9.0/linux-x64/publish/

Build succeeded in 34.3s
> dotnet publish -c Release -r linux-arm64 --self-contained
Restore complete (1.0s)
  WebApplication6 failed with 1 error(s) (2.9s) → bin/Release/net9.0/linux-arm64/WebApplication6.dll
    /home/ladeak/.nuget/packages/microsoft.dotnet.ilcompiler/9.0.0/build/Microsoft.NETCore.Native.Publish.targets(77,5): error : The PrivateSdkAssemblies ItemGroup is required for _ComputeAssembliesToCompileToNative

Build failed with 1 error(s) in 4.9s

I am on Win11 x64 (Intel). I would expect it to work, as it works on Windows (targeting the same source to win-arm64)
<PublishAot> is set in the csproj. ASP.NET Core minimal APIs app.

[richlander]

Did you look at this?

https://github.com/dotnet/runtime/blob/main/src/coreclr/nativeaot/docs/compiling.md#cross-architecture-compilation

[ladeak]

Thanks for the pointers.